diff --git a/.editorconfig b/.editorconfig
index 44e191e..61ed589 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -27,3 +27,12 @@ insert_final_newline = true
 indent_style = tab
 insert_final_newline = true
 
+[*.snippet]
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+
+[*.nix]
+indent_style = space
+indent_size = 2
+insert_final_newline = true
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 029d32a..e92c179 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -11,3 +11,27 @@ jobs:
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
       - run: nix run
+
+  build-pkg:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: nix build .#calamares-nixos-extensions
+
+  build-iso:
+    needs: build-pkg
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        name:
+          - "defaultCalamaresIso"
+          - "customCalamaresIso"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: nix build .#${{ matrix.name }}
diff --git a/.gitignore b/.gitignore
index bdd0802..6a48da8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,6 @@ build/
 *.qmlc
 .vscode/
 **/__pycache__/
+
+results
+result
diff --git a/branding/nixos/branding.desc b/branding/nixos/branding.desc
index 8666257..2a00deb 100644
--- a/branding/nixos/branding.desc
+++ b/branding/nixos/branding.desc
@@ -117,8 +117,8 @@ navigation: widget
 strings:
     productName:         "${NAME}"
     shortProductName:    NixOS
-    version:             
-    shortVersion:        
+    version:             ""
+    shortVersion:        ""
     versionedName:       NixOS
     shortVersionedName:  NixOS
     bootloaderEntryName: NixOS
diff --git a/flake.nix b/flake.nix
index c564aa6..df40a6f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,7 +5,8 @@
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
   };
 
-  outputs = { nixpkgs, ... }:
+  outputs =
+    { nixpkgs, ... }:
     let
       system = "x86_64-linux";
 
@@ -14,17 +15,51 @@
       };
 
       packages = [
-        (pkgs.python3.withPackages (pp: with pp; [ pytest pytest-mock ]))
+        (pkgs.python3.withPackages (
+          pp: with pp; [
+            pytest
+            pytest-mock
+          ]
+        ))
       ];
+
+      mkISO = (import ./nix/lib/mkISO.nix);
+      calamaresIsoBuilder =
+        nixpkgsSource: name: extraModules:
+        (mkISO name {
+          inherit
+            system
+            ;
+          inherit (nixpkgsSource) lib;
+          nixosSystem = import (nixpkgsSource + "/nixos/lib/eval-config.nix");
+          withModules = [
+            "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-graphical-calamares-gnome.nix"
+            ./nix/calamares-nixos-extensions-upstream.nix
+          ] ++ extraModules;
+        }).config.system.build.isoImage;
     in
     {
-      packages.${system}.default = pkgs.writeShellApplication {
-        name = "test-nixos-install";
-        runtimeInputs = packages;
-        text = ''
-          #!${pkgs.stdenv.shell}
-          pytest -vv testing
-        '';
+      packages.${system} = {
+        default = pkgs.writeShellApplication {
+          name = "test-nixos-install";
+          runtimeInputs = packages;
+          text = ''
+            #!${pkgs.stdenv.shell}
+            pytest -vv testing
+          '';
+        };
+
+        calamares-nixos-extensions = pkgs.callPackage ./nix/calamares-nixos-extensions/package.nix { };
+
+        defaultCalamaresIso = calamaresIsoBuilder nixpkgs "defaultCalamaresISO" [ ];
+
+        customCalamaresIso = calamaresIsoBuilder nixpkgs "customCalamaresISO" [
+          # Add custom modules to the iso (runtime)
+          ./nix/modules/virtualboxGuest.nix
+          ./nix/modules/zsh.nix
+          # Configure the calamares extension with custom snippets
+          ./nix/modules/calamares-customizations.nix
+        ];
       };
 
       devShells.${system}.default = pkgs.mkShell {
diff --git a/modules/nixos/defaultConfigs/modules/.gitkeep b/modules/nixos/defaultConfigs/modules/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/modules/nixos/defaultConfigs/snippets/audio.snippet b/modules/nixos/defaultConfigs/snippets/audio.snippet
new file mode 100644
index 0000000..0e8f2bc
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/audio.snippet
@@ -0,0 +1,15 @@
+# Enable sound with pipewire.
+hardware.pulseaudio.enable = false;
+security.rtkit.enable = true;
+services.pipewire = {
+  enable = true;
+  alsa.enable = true;
+  alsa.support32Bit = true;
+  pulse.enable = true;
+  # If you want to use JACK applications, uncomment this
+  #jack.enable = true;
+
+  # use the example session manager (no others are packaged yet so this is enabled by default,
+  # no need to redefine it in your config for now)
+  #media-session.enable = true;
+};
diff --git a/modules/nixos/defaultConfigs/snippets/autologin.snippet b/modules/nixos/defaultConfigs/snippets/autologin.snippet
new file mode 100644
index 0000000..cbba546
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/autologin.snippet
@@ -0,0 +1,3 @@
+# Enable automatic login for the user.
+services.displayManager.autoLogin.enable = true;
+services.displayManager.autoLogin.user = "@@username@@";
diff --git a/modules/nixos/defaultConfigs/snippets/autologingdm.snippet b/modules/nixos/defaultConfigs/snippets/autologingdm.snippet
new file mode 100644
index 0000000..8dcb446
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/autologingdm.snippet
@@ -0,0 +1,3 @@
+# Workaround for GNOME autologin: https://github.com/NixOS/nixpkgs/issues/103746#issuecomment-945091229
+systemd.services."getty@tty1".enable = false;
+systemd.services."autovt@tty1".enable = false;
diff --git a/modules/nixos/defaultConfigs/snippets/autologintty.snippet b/modules/nixos/defaultConfigs/snippets/autologintty.snippet
new file mode 100644
index 0000000..2221251
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/autologintty.snippet
@@ -0,0 +1,2 @@
+# Enable automatic login for the user.
+services.getty.autologinUser = "@@username@@";
diff --git a/modules/nixos/defaultConfigs/snippets/bootbios.snippet b/modules/nixos/defaultConfigs/snippets/bootbios.snippet
new file mode 100644
index 0000000..f3b6b9a
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/bootbios.snippet
@@ -0,0 +1,5 @@
+# Bootloader.
+boot.loader.grub.enable = true;
+boot.loader.grub.device = "@@bootdev@@";
+boot.loader.grub.useOSProber = true;
+boot.tmp.useTmpfs = true;
diff --git a/modules/nixos/defaultConfigs/snippets/bootefi.snippet b/modules/nixos/defaultConfigs/snippets/bootefi.snippet
new file mode 100644
index 0000000..63dcbd5
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/bootefi.snippet
@@ -0,0 +1,5 @@
+# Bootloader.
+boot.loader.systemd-boot.enable = true;
+boot.loader.systemd-boot.configurationLimit = 42;
+boot.loader.efi.canTouchEfiVariables = true;
+boot.tmp.useTmpfs = true;
diff --git a/modules/nixos/defaultConfigs/snippets/bootgrubcrypt.snippet b/modules/nixos/defaultConfigs/snippets/bootgrubcrypt.snippet
new file mode 100644
index 0000000..fcf73dc
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/bootgrubcrypt.snippet
@@ -0,0 +1,6 @@
+# Setup keyfile
+boot.initrd.secrets = {
+  "/boot/crypto_keyfile.bin" = null;
+};
+
+boot.loader.grub.enableCryptodisk = true;
diff --git a/modules/nixos/defaultConfigs/snippets/bootnone.snippet b/modules/nixos/defaultConfigs/snippets/bootnone.snippet
new file mode 100644
index 0000000..4437d2f
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/bootnone.snippet
@@ -0,0 +1,2 @@
+# Disable bootloader.
+boot.loader.grub.enable = false;
diff --git a/modules/nixos/defaultConfigs/snippets/connman.snippet b/modules/nixos/defaultConfigs/snippets/connman.snippet
new file mode 100644
index 0000000..474f603
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/connman.snippet
@@ -0,0 +1,2 @@
+# Enable networking
+services.connman.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/console.snippet b/modules/nixos/defaultConfigs/snippets/console.snippet
new file mode 100644
index 0000000..6f923b0
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/console.snippet
@@ -0,0 +1,2 @@
+# Configure console keymap
+console.keyMap = "@@vconsole@@";
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/budgie.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/budgie.snippet
new file mode 100644
index 0000000..f1f55b7
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/budgie.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Budgie Desktop environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.budgie.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/cinnamon.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/cinnamon.snippet
new file mode 100644
index 0000000..34ac658
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/cinnamon.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Cinnamon Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.cinnamon.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/deepin.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/deepin.snippet
new file mode 100644
index 0000000..3312420
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/deepin.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Deepin Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.deepin.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/enlightment.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/enlightment.snippet
new file mode 100644
index 0000000..afb2034
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/enlightment.snippet
@@ -0,0 +1,9 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Enlightenment Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.enlightenment.enable = true;
+
+# Enable acpid
+services.acpid.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/gnome.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/gnome.snippet
new file mode 100644
index 0000000..9fddc73
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/gnome.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the GNOME Desktop Environment.
+services.xserver.displayManager.gdm.enable = true;
+services.xserver.desktopManager.gnome.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/lumina.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/lumina.snippet
new file mode 100644
index 0000000..2301f58
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/lumina.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Lumina Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.lumina.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/lxqt.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/lxqt.snippet
new file mode 100644
index 0000000..fd91369
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/lxqt.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the LXQT Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.lxqt.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/mate.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/mate.snippet
new file mode 100644
index 0000000..a92a464
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/mate.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the MATE Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.mate.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/pantheon.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/pantheon.snippet
new file mode 100644
index 0000000..3cb439f
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/pantheon.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the Pantheon Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.pantheon.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/plasma6.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/plasma6.snippet
new file mode 100644
index 0000000..f220a53
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/plasma6.snippet
@@ -0,0 +1,7 @@
+# Enable the X11 windowing system.
+# You can disable this if you're only using the Wayland session.
+services.xserver.enable = true;
+
+# Enable the KDE Plasma Desktop Environment.
+services.displayManager.sddm.enable = true;
+services.desktopManager.plasma6.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/desktopEnv/xfce.snippet b/modules/nixos/defaultConfigs/snippets/desktopEnv/xfce.snippet
new file mode 100644
index 0000000..ec47f6d
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/desktopEnv/xfce.snippet
@@ -0,0 +1,6 @@
+# Enable the X11 windowing system.
+services.xserver.enable = true;
+
+# Enable the XFCE Desktop Environment.
+services.xserver.displayManager.lightdm.enable = true;
+services.xserver.desktopManager.xfce.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/extra.snippet b/modules/nixos/defaultConfigs/snippets/extra.snippet
new file mode 100644
index 0000000..0fb53a1
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/extra.snippet
@@ -0,0 +1,18 @@
+# Some programs need SUID wrappers, can be configured further or are
+# started in user sessions.
+# programs.mtr.enable = true;
+# programs.gnupg.agent = {
+#   enable = true;
+#   enableSSHSupport = true;
+# };
+
+# List services that you want to enable:
+
+# Enable the OpenSSH daemon.
+# services.openssh.enable = true;
+
+# Open ports in the firewall.
+# networking.firewall.allowedTCPPorts = [ ... ];
+# networking.firewall.allowedUDPPorts = [ ... ];
+# Or disable the firewall altogether.
+# networking.firewall.enable = false;
diff --git a/modules/nixos/defaultConfigs/snippets/firefox.snippet b/modules/nixos/defaultConfigs/snippets/firefox.snippet
new file mode 100644
index 0000000..b91722e
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/firefox.snippet
@@ -0,0 +1 @@
+programs.firefox.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/head.snippet b/modules/nixos/defaultConfigs/snippets/head.snippet
new file mode 100644
index 0000000..b2b148b
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/head.snippet
@@ -0,0 +1,7 @@
+# Edit this configuration file to define what should be installed on
+# your system.  Help is available in the configuration.nix(5) man page
+# and in the NixOS manual (accessible by running ‘nixos-help’).
+
+{ config, pkgs, ... }:
+
+{
diff --git a/modules/nixos/defaultConfigs/snippets/imports.snippet b/modules/nixos/defaultConfigs/snippets/imports.snippet
new file mode 100644
index 0000000..04b88df
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/imports.snippet
@@ -0,0 +1,5 @@
+imports =
+  [
+    # Include the results of the hardware scan.
+    ./hardware-configuration.nix
+  ];
diff --git a/modules/nixos/defaultConfigs/snippets/keymap.snippet b/modules/nixos/defaultConfigs/snippets/keymap.snippet
new file mode 100644
index 0000000..887d0d9
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/keymap.snippet
@@ -0,0 +1,5 @@
+# Configure keymap in X11
+services.xserver.xkb = {
+    layout = "@@kblayout@@";
+    variant = "@@kbvariant@@";
+};
diff --git a/modules/nixos/defaultConfigs/snippets/latestkernel.snippet b/modules/nixos/defaultConfigs/snippets/latestkernel.snippet
new file mode 100644
index 0000000..25ce6eb
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/latestkernel.snippet
@@ -0,0 +1,2 @@
+  # Use latest kernel.
+  boot.kernelPackages = pkgs.linuxPackages_latest;
diff --git a/modules/nixos/defaultConfigs/snippets/locale.snippet b/modules/nixos/defaultConfigs/snippets/locale.snippet
new file mode 100644
index 0000000..61e3333
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/locale.snippet
@@ -0,0 +1,2 @@
+# Select internationalisation properties.
+i18n.defaultLocale = "@@LANG@@";
diff --git a/modules/nixos/defaultConfigs/snippets/localeextra.snippet b/modules/nixos/defaultConfigs/snippets/localeextra.snippet
new file mode 100644
index 0000000..596859f
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/localeextra.snippet
@@ -0,0 +1,11 @@
+i18n.extraLocaleSettings = {
+  LC_ADDRESS = "@@LC_ADDRESS@@";
+  LC_IDENTIFICATION = "@@LC_IDENTIFICATION@@";
+  LC_MEASUREMENT = "@@LC_MEASUREMENT@@";
+  LC_MONETARY = "@@LC_MONETARY@@";
+  LC_NAME = "@@LC_NAME@@";
+  LC_NUMERIC = "@@LC_NUMERIC@@";
+  LC_PAPER = "@@LC_PAPER@@";
+  LC_TELEPHONE = "@@LC_TELEPHONE@@";
+  LC_TIME = "@@LC_TIME@@";
+};
diff --git a/modules/nixos/defaultConfigs/snippets/misc.snippet b/modules/nixos/defaultConfigs/snippets/misc.snippet
new file mode 100644
index 0000000..e2884bc
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/misc.snippet
@@ -0,0 +1,5 @@
+# Enable CUPS to print documents.
+services.printing.enable = true;
+
+# Enable touchpad support (enabled default in most desktopManager).
+# services.xserver.libinput.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/network.snippet b/modules/nixos/defaultConfigs/snippets/network.snippet
new file mode 100644
index 0000000..20c05e2
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/network.snippet
@@ -0,0 +1,6 @@
+networking.hostName = "@@hostname@@"; # Define your hostname.
+# networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
+
+# Configure network proxy if necessary
+# networking.proxy.default = "http://user:password@proxy:port/";
+# networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
diff --git a/modules/nixos/defaultConfigs/snippets/networkmanager.snippet b/modules/nixos/defaultConfigs/snippets/networkmanager.snippet
new file mode 100644
index 0000000..09ec6b7
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/networkmanager.snippet
@@ -0,0 +1 @@
+networking.networkmanager.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/nmapplet.snippet b/modules/nixos/defaultConfigs/snippets/nmapplet.snippet
new file mode 100644
index 0000000..5139163
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/nmapplet.snippet
@@ -0,0 +1,2 @@
+# Enable network manager applet
+programs.nm-applet.enable = true;
diff --git a/modules/nixos/defaultConfigs/snippets/pkgs.snippet b/modules/nixos/defaultConfigs/snippets/pkgs.snippet
new file mode 100644
index 0000000..4bfc6ed
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/pkgs.snippet
@@ -0,0 +1,6 @@
+# List packages installed in system profile. To search, run:
+# $ nix search wget
+environment.systemPackages = with pkgs; [
+#  vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
+#  wget
+];
diff --git a/modules/nixos/defaultConfigs/snippets/tail.snippet b/modules/nixos/defaultConfigs/snippets/tail.snippet
new file mode 100644
index 0000000..1b74304
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/tail.snippet
@@ -0,0 +1,9 @@
+# This value determines the NixOS release from which the default
+# settings for stateful data, like file locations and database versions
+# on your system were taken. It‘s perfectly fine and recommended to leave
+# this value at the release version of the first install of this system.
+# Before changing this value read the documentation for this option
+# (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+system.stateVersion = "@@nixosversion@@"; # Did you read the comment?
+
+}
diff --git a/modules/nixos/defaultConfigs/snippets/time.snippet b/modules/nixos/defaultConfigs/snippets/time.snippet
new file mode 100644
index 0000000..769ec59
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/time.snippet
@@ -0,0 +1 @@
+time.timeZone = "@@timezone@@";
diff --git a/modules/nixos/defaultConfigs/snippets/unfree.snippet b/modules/nixos/defaultConfigs/snippets/unfree.snippet
new file mode 100644
index 0000000..18d7a2e
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/unfree.snippet
@@ -0,0 +1,2 @@
+# Allow unfree packages
+nixpkgs.config.allowUnfree = true;
diff --git a/modules/nixos/defaultConfigs/snippets/users.snippet b/modules/nixos/defaultConfigs/snippets/users.snippet
new file mode 100644
index 0000000..0ff21a8
--- /dev/null
+++ b/modules/nixos/defaultConfigs/snippets/users.snippet
@@ -0,0 +1,7 @@
+# Define a user account. Don't forget to set a password with ‘passwd’.
+users.users.@@username@@ = {
+  isNormalUser = true;
+  description = "@@fullname@@";
+  extraGroups = [ @@groups@@ ];
+  packages = with pkgs; [@@pkgs@@];
+};
diff --git a/modules/nixos/main.py b/modules/nixos/main.py
index b1721a9..095aa92 100644
--- a/modules/nixos/main.py
+++ b/modules/nixos/main.py
@@ -23,316 +23,44 @@
     fallback=True,
 ).gettext
 
+def getCalamaresNixosModulePath():
+    return '/run/current-system/sw/lib/calamares/modules/nixos'
 
-# The following strings contain pieces of a nix-configuration file.
-# They are adapted from the default config generated from the nixos-generate-config command.
+def getCustomOrDefaultSnippet(snippetName):
+    configPath = getCalamaresNixosModulePath()
 
-cfghead = """# Edit this configuration file to define what should be installed on
-# your system.  Help is available in the configuration.nix(5) man page
-# and in the NixOS manual (accessible by running ‘nixos-help’).
+    # Check if a custom snippet exists for the config name
+    snippetConfigPath = '{}/defaultConfigs/snippets/{}.snippet'.format(configPath, snippetName)
+    customConfigFilePath = '{}/customConfigs/snippets/{}.snippet'.format(configPath, snippetName)
 
-{ config, pkgs, ... }:
-
-{
-  imports =
-    [ # Include the results of the hardware scan.
-      ./hardware-configuration.nix
-    ];
-
-"""
-cfgbootefi = """  # Bootloader.
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
-
-"""
-
-cfgbootbios = """  # Bootloader.
-  boot.loader.grub.enable = true;
-  boot.loader.grub.device = "@@bootdev@@";
-  boot.loader.grub.useOSProber = true;
-
-"""
-
-cfgbootnone = """  # Disable bootloader.
-  boot.loader.grub.enable = false;
-
-"""
-
-cfgbootgrubcrypt = """  # Setup keyfile
-  boot.initrd.secrets = {
-    "/boot/crypto_keyfile.bin" = null;
-  };
-
-  boot.loader.grub.enableCryptodisk = true;
-
-"""
-
-cfgnetwork = """  networking.hostName = "@@hostname@@"; # Define your hostname.
-  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
-
-  # Configure network proxy if necessary
-  # networking.proxy.default = "http://user:password@proxy:port/";
-  # networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
-
-"""
-
-cfgnetworkmanager = """  # Enable networking
-  networking.networkmanager.enable = true;
-
-"""
-
-cfgconnman = """  # Enable networking
-  services.connman.enable = true;
-
-"""
-
-cfgnmapplet = """  # Enable network manager applet
-  programs.nm-applet.enable = true;
-
-"""
-
-cfgtime = """  # Set your time zone.
-  time.timeZone = "@@timezone@@";
-
-"""
-
-cfglocale = """  # Select internationalisation properties.
-  i18n.defaultLocale = "@@LANG@@";
-
-"""
-
-cfglocaleextra = """  i18n.extraLocaleSettings = {
-    LC_ADDRESS = "@@LC_ADDRESS@@";
-    LC_IDENTIFICATION = "@@LC_IDENTIFICATION@@";
-    LC_MEASUREMENT = "@@LC_MEASUREMENT@@";
-    LC_MONETARY = "@@LC_MONETARY@@";
-    LC_NAME = "@@LC_NAME@@";
-    LC_NUMERIC = "@@LC_NUMERIC@@";
-    LC_PAPER = "@@LC_PAPER@@";
-    LC_TELEPHONE = "@@LC_TELEPHONE@@";
-    LC_TIME = "@@LC_TIME@@";
-  };
-
-"""
-
-cfggnome = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the GNOME Desktop Environment.
-  services.xserver.displayManager.gdm.enable = true;
-  services.xserver.desktopManager.gnome.enable = true;
-
-"""
-
-cfgplasma6 = """  # Enable the X11 windowing system.
-  # You can disable this if you're only using the Wayland session.
-  services.xserver.enable = true;
-
-  # Enable the KDE Plasma Desktop Environment.
-  services.displayManager.sddm.enable = true;
-  services.desktopManager.plasma6.enable = true;
-
-"""
-
-cfgxfce = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the XFCE Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.xfce.enable = true;
-
-"""
-
-cfgpantheon = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Pantheon Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.pantheon.enable = true;
-
-"""
-
-cfgcinnamon = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Cinnamon Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.cinnamon.enable = true;
-
-"""
-
-cfgmate = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the MATE Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.mate.enable = true;
-
-"""
-
-cfgenlightenment = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Enlightenment Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.enlightenment.enable = true;
-
-  # Enable acpid
-  services.acpid.enable = true;
-
-"""
-
-cfglxqt = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the LXQT Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.lxqt.enable = true;
-
-"""
-
-cfglumina = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Lumina Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.lumina.enable = true;
-
-"""
-
-cfgbudgie = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Budgie Desktop environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.budgie.enable = true;
-
-"""
-
-cfgdeepin = """  # Enable the X11 windowing system.
-  services.xserver.enable = true;
-
-  # Enable the Deepin Desktop Environment.
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.deepin.enable = true;
-
-"""
-
-cfgkeymap = """  # Configure keymap in X11
-  services.xserver.xkb = {
-    layout = "@@kblayout@@";
-    variant = "@@kbvariant@@";
-  };
-
-"""
-cfgconsole = """  # Configure console keymap
-  console.keyMap = "@@vconsole@@";
-
-"""
-
-cfgmisc = """  # Enable CUPS to print documents.
-  services.printing.enable = true;
-
-  # Enable sound with pipewire.
-  hardware.pulseaudio.enable = false;
-  security.rtkit.enable = true;
-  services.pipewire = {
-    enable = true;
-    alsa.enable = true;
-    alsa.support32Bit = true;
-    pulse.enable = true;
-    # If you want to use JACK applications, uncomment this
-    #jack.enable = true;
-
-    # use the example session manager (no others are packaged yet so this is enabled by default,
-    # no need to redefine it in your config for now)
-    #media-session.enable = true;
-  };
-
-  # Enable touchpad support (enabled default in most desktopManager).
-  # services.xserver.libinput.enable = true;
-
-"""
-cfgusers = """  # Define a user account. Don't forget to set a password with ‘passwd’.
-  users.users.@@username@@ = {
-    isNormalUser = true;
-    description = "@@fullname@@";
-    extraGroups = [ @@groups@@ ];
-    packages = with pkgs; [@@pkgs@@];
-  };
-
-"""
-
-cfgfirefox = """  # Install firefox.
-  programs.firefox.enable = true;
-
-"""
-
-cfgautologin = """  # Enable automatic login for the user.
-  services.displayManager.autoLogin.enable = true;
-  services.displayManager.autoLogin.user = "@@username@@";
-
-"""
-
-cfgautologingdm = """  # Workaround for GNOME autologin: https://github.com/NixOS/nixpkgs/issues/103746#issuecomment-945091229
-  systemd.services."getty@tty1".enable = false;
-  systemd.services."autovt@tty1".enable = false;
-
-"""
-
-cfgautologintty = """  # Enable automatic login for the user.
-  services.getty.autologinUser = "@@username@@";
-
-"""
-
-cfgunfree = """  # Allow unfree packages
-  nixpkgs.config.allowUnfree = true;
-
-"""
-
-cfgpkgs = """  # List packages installed in system profile. To search, run:
-  # $ nix search wget
-  environment.systemPackages = with pkgs; [
-  #  vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
-  #  wget
-  ];
-
-"""
-
-cfgtail = """  # Some programs need SUID wrappers, can be configured further or are
-  # started in user sessions.
-  # programs.mtr.enable = true;
-  # programs.gnupg.agent = {
-  #   enable = true;
-  #   enableSSHSupport = true;
-  # };
-
-  # List services that you want to enable:
-
-  # Enable the OpenSSH daemon.
-  # services.openssh.enable = true;
-
-  # Open ports in the firewall.
-  # networking.firewall.allowedTCPPorts = [ ... ];
-  # networking.firewall.allowedUDPPorts = [ ... ];
-  # Or disable the firewall altogether.
-  # networking.firewall.enable = false;
-
-  # This value determines the NixOS release from which the default
-  # settings for stateful data, like file locations and database versions
-  # on your system were taken. It‘s perfectly fine and recommended to leave
-  # this value at the release version of the first install of this system.
-  # Before changing this value read the documentation for this option
-  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
-  system.stateVersion = "@@nixosversion@@"; # Did you read the comment?
-
-}
-"""
-
-cfglatestkernel = """  # Use latest kernel.
-  boot.kernelPackages = pkgs.linuxPackages_latest;
+    if os.path.isfile(customConfigFilePath):
+        libcalamares.utils.debug('Selected custom snippet: {} from {}'.format(snippetName, customConfigFilePath))
+        snippetConfigPath = customConfigFilePath
+    else:
+        libcalamares.utils.debug('Selected default snippet: {} from {}'.format(snippetName, snippetConfigPath))
+
+    # load config
+    with open(snippetConfigPath, 'r') as configReader:
+        snippet = configReader.read()
+        snippet += '\n'
+        return snippet
+
+    libcalamares.utils.error('Failed to load config snippet {}'.format(snippetName))
+    return ""
+
+def copyModules(root_mount_point, subpath):
+    srcModuleFolderPath = '{}/{}/.'.format(getCalamaresNixosModulePath(), subpath)
+    destModuleFolderPath = '{}/etc/nixos/modules/'.format(root_mount_point)
+    if os.path.isdir(srcModuleFolderPath) and len(os.listdir(srcModuleFolderPath)) != 0:
+        if not os.path.isdir(destModuleFolderPath):
+            libcalamares.utils.host_env_process_output(
+                ["mkdir", "-p", destModuleFolderPath], None
+            )
+        libcalamares.utils.debug('Copying module directory {}'.format(srcModuleFolderPath))
+        libcalamares.utils.host_env_process_output(["cp", "-r", srcModuleFolderPath, destModuleFolderPath], None)
+    else:
+        libcalamares.utils.debug('Skipping non-existing module directory {}'.format(srcModuleFolderPath))
 
-"""
 def env_is_set(name):
     envValue = os.environ.get(name)
     return not (envValue is None or envValue == "")
@@ -353,6 +81,16 @@ def generateProxyStrings():
 
     return proxyEnv
 
+def generateNixOptionStringFromHost(optionName):
+    out = subprocess.run(["nix", "config", "show", optionName], capture_output=True, text=True)
+    if out.returncode == 0:
+        return [
+            "--option",
+            optionName,
+            out.stdout.strip()
+        ]
+    return []
+
 def pretty_name():
     return _("Installing NixOS.")
 
@@ -389,7 +127,8 @@ def run():
     ngc_cfg.read("/etc/nixos-generate-config.conf")
 
     # Create initial config file
-    cfg = cfghead
+    cfg = getCustomOrDefaultSnippet('head')
+    cfg += getCustomOrDefaultSnippet('imports')
     gs = libcalamares.globalstorage
     variables = dict()
 
@@ -407,15 +146,15 @@ def run():
 
     # Check bootloader
     if fw_type == "efi":
-        cfg += cfgbootefi
+        cfg += getCustomOrDefaultSnippet('bootefi')
     elif bootdev != "nodev":
-        cfg += cfgbootbios
+        cfg += getCustomOrDefaultSnippet('bootbios')
         catenate(variables, "bootdev", bootdev)
     else:
-        cfg += cfgbootnone
+        cfg += getCustomOrDefaultSnippet('bootnone')
 
     if ngc_cfg["Defaults"]["Kernel"] == "latest":
-        cfg += cfglatestkernel
+        cfg += getCustomOrDefaultSnippet('latestkernel')
 
     # Setup encrypted swap devices. nixos-generate-config doesn't seem to notice them.
     for part in gs.value("partitions"):
@@ -446,7 +185,7 @@ def run():
         (boot_is_partition and boot_is_encrypted)
         or (root_is_encrypted and not boot_is_partition)
     ):
-        cfg += cfgbootgrubcrypt
+        cfg += getCustomOrDefaultSnippet('bootgrubcrypt')
         status = _("Setting up LUKS")
         libcalamares.job.setprogress(0.15)
         try:
@@ -535,18 +274,18 @@ def run():
     status = _("Configuring NixOS")
     libcalamares.job.setprogress(0.18)
 
-    cfg += cfgnetwork
+    cfg += getCustomOrDefaultSnippet('network')
     if gs.value("packagechooser_packagechooser") == "enlightenment":
-        cfg += cfgconnman
+        cfg += getCustomOrDefaultSnippet('connman')
     else:
-        cfg += cfgnetworkmanager
+        cfg += getCustomOrDefaultSnippet('networkmanager')
 
     if (
         (gs.value("packagechooser_packagechooser") == "mate")
         | (gs.value("packagechooser_packagechooser") == "lxqt")
         | (gs.value("packagechooser_packagechooser") == "lumina")
     ):
-        cfg += cfgnmapplet
+        cfg += getCustomOrDefaultSnippet('nmapplet')
 
     if gs.value("hostname") is None:
         catenate(variables, "hostname", "nixos")
@@ -554,7 +293,7 @@ def run():
         catenate(variables, "hostname", gs.value("hostname"))
 
     if gs.value("locationRegion") is not None and gs.value("locationZone") is not None:
-        cfg += cfgtime
+        cfg += getCustomOrDefaultSnippet('time')
         catenate(
             variables,
             "timezone",
@@ -566,45 +305,45 @@ def run():
     if gs.value("localeConf") is not None:
         localeconf = gs.value("localeConf")
         locale = localeconf.pop("LANG").split("/")[0]
-        cfg += cfglocale
+        cfg += getCustomOrDefaultSnippet('locale')
         catenate(variables, "LANG", locale)
         if (
             len(set(localeconf.values())) != 1
             or list(set(localeconf.values()))[0] != locale
         ):
-            cfg += cfglocaleextra
+            cfg += getCustomOrDefaultSnippet('localeextra')
             for conf in localeconf:
                 catenate(variables, conf, localeconf.get(conf).split("/")[0])
 
     # Choose desktop environment
     if gs.value("packagechooser_packagechooser") == "gnome":
-        cfg += cfggnome
+        cfg += getCustomOrDefaultSnippet('desktopEnv/gnome')
     elif gs.value("packagechooser_packagechooser") == "plasma6":
-        cfg += cfgplasma6
+        cfg += getCustomOrDefaultSnippet('desktopEnv/plasma6')
     elif gs.value("packagechooser_packagechooser") == "xfce":
-        cfg += cfgxfce
+        cfg += getCustomOrDefaultSnippet('desktopEnv/xfce')
     elif gs.value("packagechooser_packagechooser") == "pantheon":
-        cfg += cfgpantheon
+        cfg += getCustomOrDefaultSnippet('desktopEnv/pantheon')
     elif gs.value("packagechooser_packagechooser") == "cinnamon":
-        cfg += cfgcinnamon
+        cfg += getCustomOrDefaultSnippet('desktopEnv/cinnamon')
     elif gs.value("packagechooser_packagechooser") == "mate":
-        cfg += cfgmate
+        cfg += getCustomOrDefaultSnippet('desktopEnv/mate')
     elif gs.value("packagechooser_packagechooser") == "enlightenment":
-        cfg += cfgenlightenment
+        cfg += getCustomOrDefaultSnippet('desktopEnv/enlightenment')
     elif gs.value("packagechooser_packagechooser") == "lxqt":
-        cfg += cfglxqt
+        cfg += getCustomOrDefaultSnippet('desktopEnv/lxqt')
     elif gs.value("packagechooser_packagechooser") == "lumina":
-        cfg += cfglumina
+        cfg += getCustomOrDefaultSnippet('desktopEnv/lumina')
     elif gs.value("packagechooser_packagechooser") == "budgie":
-        cfg += cfgbudgie
+        cfg += getCustomOrDefaultSnippet('desktopEnv/budgie')
     elif gs.value("packagechooser_packagechooser") == "deepin":
-        cfg += cfgdeepin
+        cfg += getCustomOrDefaultSnippet('desktopEnv/deepin')
 
     if (
         gs.value("keyboardLayout") is not None
         and gs.value("keyboardVariant") is not None
     ):
-        cfg += cfgkeymap
+        cfg += getCustomOrDefaultSnippet('keymap')
         catenate(variables, "kblayout", gs.value("keyboardLayout"))
         catenate(variables, "kbvariant", gs.value("keyboardVariant"))
 
@@ -614,7 +353,7 @@ def run():
                     ["pkexec", "loadkeys", gs.value("keyboardVConsoleKeymap").strip()],
                     stderr=subprocess.STDOUT,
                 )
-                cfg += cfgconsole
+                cfg += getCustomOrDefaultSnippet('console')
                 catenate(
                     variables, "vconsole", gs.value("keyboardVConsoleKeymap").strip()
                 )
@@ -659,7 +398,7 @@ def run():
                     subprocess.check_output(
                         ["pkexec", "loadkeys", vconsole], stderr=subprocess.STDOUT
                     )
-                    cfg += cfgconsole
+                    cfg += getCustomOrDefaultSnippet('console')
                     catenate(variables, "vconsole", vconsole)
                 except subprocess.CalledProcessError as e:
                     libcalamares.utils.error("loadkeys: {}".format(e.output))
@@ -674,13 +413,14 @@ def run():
         gs.value("packagechooser_packagechooser") is not None
         and gs.value("packagechooser_packagechooser") != ""
     ):
-        cfg += cfgmisc
+        cfg += getCustomOrDefaultSnippet('misc')
+        cfg += getCustomOrDefaultSnippet('audio')
 
     if gs.value("username") is not None:
         fullname = gs.value("fullname")
         groups = ["networkmanager", "wheel"]
 
-        cfg += cfgusers
+        cfg += getCustomOrDefaultSnippet('users')
         catenate(variables, "username", gs.value("username"))
         catenate(variables, "fullname", fullname)
         catenate(variables, "groups", (" ").join(['"' + s + '"' for s in groups]))
@@ -689,23 +429,23 @@ def run():
             and gs.value("packagechooser_packagechooser") is not None
             and gs.value("packagechooser_packagechooser") != ""
         ):
-            cfg += cfgautologin
+            cfg += getCustomOrDefaultSnippet('autologin')
             if gs.value("packagechooser_packagechooser") == "gnome":
-                cfg += cfgautologingdm
+                cfg += getCustomOrDefaultSnippet('autologingdm')
         elif gs.value("autoLoginUser") is not None:
-            cfg += cfgautologintty
+            cfg += getCustomOrDefaultSnippet('autologintty')
 
     if gs.value("packagechooser_packagechooser") != "":
-        cfg += cfgfirefox
+        cfg += getCustomOrDefaultSnippet('firefox')
 
     # Check if unfree packages are allowed
     free = True
     if gs.value("packagechooser_unfree") is not None:
         if gs.value("packagechooser_unfree") == "unfree":
             free = False
-            cfg += cfgunfree
+            cfg += getCustomOrDefaultSnippet('unfree')
 
-    cfg += cfgpkgs
+    cfg += getCustomOrDefaultSnippet('pkgs')
     # Use firefox as default as a graphical web browser, and add kate to plasma desktop
     if gs.value("packagechooser_packagechooser") == "plasma6":
         catenate(
@@ -716,7 +456,9 @@ def run():
     else:
         catenate(variables, "pkgs", "")
 
-    cfg += cfgtail
+    cfg += getCustomOrDefaultSnippet('extra')
+
+    cfg += getCustomOrDefaultSnippet('tail')
     version = ".".join(subprocess.getoutput(["nixos-version"]).split(".")[:2])[:5]
     catenate(variables, "nixosversion", version)
 
@@ -805,6 +547,12 @@ def run():
 
     # Write the configuration.nix file
     libcalamares.utils.host_env_process_output(["cp", "/dev/stdin", config], None, cfg)
+    # Format configuration file
+    libcalamares.utils.host_env_process_output(["nixfmt",  config], None)
+
+    # Copy modules
+    copyModules(root_mount_point, 'defaultConfigs/modules')
+    copyModules(root_mount_point, 'customConfigs/modules')
 
     status = _("Installing NixOS")
     libcalamares.job.setprogress(0.3)
@@ -821,6 +569,12 @@ def run():
         ]
     )
 
+    # use all substituters from the installer in nixos-install
+    nixosInstallCmd.extend(generateNixOptionStringFromHost("substituters"))
+    nixosInstallCmd.extend(generateNixOptionStringFromHost("trusted-public-keys"))
+
+    libcalamares.utils.debug('Install CMD: {}'.format(nixosInstallCmd))
+
     # Install customizations
     try:
         output = ""
diff --git a/nix/calamares-nixos-extensions-upstream.nix b/nix/calamares-nixos-extensions-upstream.nix
new file mode 100644
index 0000000..db39281
--- /dev/null
+++ b/nix/calamares-nixos-extensions-upstream.nix
@@ -0,0 +1,22 @@
+{
+  lib,
+  ...
+}:
+{
+  imports = [
+    ./calamares-nixos-extensions/module.nix
+  ];
+
+  nixpkgs.overlays = lib.mkBefore [
+    (final: prev: {
+      calamares-nixos-extensions = final.callPackage ./calamares-nixos-extensions/package.nix { };
+    })
+  ];
+
+  programs.calamares-nixos-extensions-upstream = {
+    enable = true;
+    autoStart = true;
+  };
+
+  # TODO disable programs.calamres-nixos-extensions (from nixpkgs)
+}
diff --git a/nix/calamares-nixos-extensions/module.nix b/nix/calamares-nixos-extensions/module.nix
new file mode 100644
index 0000000..dc7317e
--- /dev/null
+++ b/nix/calamares-nixos-extensions/module.nix
@@ -0,0 +1,139 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.programs.calamares-nixos-extensions-upstream;
+
+  calamaresOptionHelper =
+    description:
+    (lib.mkOption {
+      default = "";
+      type = lib.types.str;
+      description = description;
+    });
+
+  calamares-nixos-autostart = pkgs.makeAutostartItem {
+    name = "io.calamares.calamares";
+    package = pkgs.calamares-nixos;
+  };
+
+  readModulePathsToAttrSet =
+    list:
+    builtins.listToAttrs (
+      map (path: {
+        name = (baseNameOf path);
+        value = (builtins.readFile path);
+      }) list
+    );
+
+  createImportsFileStrIfNotEmpty =
+    list:
+    (
+      if (list == [ ]) then
+        ""
+      else
+        (
+          ''
+            imports = [
+          ''
+          + lib.concatStringsSep "\n" list
+          + "\n"
+          + ''
+            ];
+          ''
+        )
+    );
+in
+
+{
+  options.programs.calamares-nixos-extensions-upstream = {
+    enable = lib.mkEnableOption "the calamares based NixOS installer";
+    autoStart = lib.mkEnableOption " autostart of the installer";
+
+    snippets = {
+      modules = lib.mkOption {
+        type = lib.types.listOf lib.types.path;
+        default = [ ];
+        description = "List of module paths that should be available in the installer";
+      };
+
+      imports = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [ ];
+        description = "List of modules that should be included in configuration.nix";
+      };
+
+      desktopEnv = {
+        budgie = calamaresOptionHelper "";
+        cinnamon = calamaresOptionHelper "";
+        deepin = calamaresOptionHelper "";
+        enlightment = calamaresOptionHelper "";
+        gnome = calamaresOptionHelper "";
+        lumnia = calamaresOptionHelper "";
+        lxqt = calamaresOptionHelper "";
+        mate = calamaresOptionHelper "";
+        pantheon = calamaresOptionHelper "";
+        plasma6 = calamaresOptionHelper "";
+        xfce = calamaresOptionHelper "";
+      };
+
+      audio = calamaresOptionHelper "";
+      autologin = calamaresOptionHelper "";
+      autologindm = calamaresOptionHelper "";
+      autologintty = calamaresOptionHelper "";
+      bootbios = calamaresOptionHelper "";
+      bootefi = calamaresOptionHelper "";
+      bootgrubcrypt = calamaresOptionHelper "";
+      bootnone = calamaresOptionHelper "";
+      connman = calamaresOptionHelper "";
+      console = calamaresOptionHelper "";
+      extra = calamaresOptionHelper "";
+      firefox = calamaresOptionHelper "";
+      head = calamaresOptionHelper "";
+      keymap = calamaresOptionHelper "";
+      locale = calamaresOptionHelper "";
+      localextra = calamaresOptionHelper "";
+      misc = calamaresOptionHelper "";
+      network = calamaresOptionHelper "";
+      networkmanager = calamaresOptionHelper "";
+      nmapplet = calamaresOptionHelper "";
+      pkgs = calamaresOptionHelper "";
+      time = calamaresOptionHelper "";
+      unfree = calamaresOptionHelper "";
+      users = calamaresOptionHelper "";
+    };
+  };
+
+  ###### implementation
+
+  # nix pkg overlay mit attr over
+
+  config = lib.mkIf cfg.enable {
+    environment.systemPackages =
+      with pkgs;
+      [
+        libsForQt5.kpmcore
+        calamares-nixos
+        calamares-nixos-extensions
+        nixfmt-rfc-style
+        # Get list of locales
+        glibcLocales
+      ]
+      ++ (lib.optionals (cfg.autoStart) [ calamares-nixos-autostart ]);
+
+    nixpkgs.overlays = [
+      (self: super: {
+        calamares-nixos-extensions = super.calamares-nixos-extensions.override {
+          snippets = cfg.snippets // {
+            modules = readModulePathsToAttrSet cfg.snippets.modules;
+            imports = createImportsFileStrIfNotEmpty cfg.snippets.imports;
+          };
+        };
+      })
+    ];
+  };
+}
diff --git a/nix/calamares-nixos-extensions/package.nix b/nix/calamares-nixos-extensions/package.nix
new file mode 100644
index 0000000..9241fe8
--- /dev/null
+++ b/nix/calamares-nixos-extensions/package.nix
@@ -0,0 +1,92 @@
+{
+  lib,
+  nix-gitignore,
+  nixfmt-rfc-style,
+  stdenv,
+  writeText,
+  snippets ? { },
+}:
+let
+  calamaresSnippetHelper =
+    type: subDir: name: filenameFunction: value:
+    (
+      let
+        outPath = "$out/lib/calamares/modules/nixos/customConfigs/${type}/${subDir}/${filenameFunction name}";
+        snippetStorePath = writeText name value;
+      in
+      lib.optionalString (
+        lib.typeOf value == "string" && value != ""
+      ) "cp ${snippetStorePath} ${lib.strings.normalizePath outPath}\n"
+    );
+  calamaresSnippetHelperWriteAttrSet =
+    type: subDir: filenameFunction: attrSet:
+    (lib.concatStringsSep "\n" (
+      lib.mapAttrsToList (
+        name: value: (calamaresSnippetHelper type subDir name filenameFunction value)
+      ) attrSet
+    ));
+  nameToSnippetName = name: ("${name}.snippet");
+  nameToName = name: name;
+  calamaresSnippetHelperWriteAttrSetSnippets =
+    type: subDir: attrSet:
+    (calamaresSnippetHelperWriteAttrSet type subDir nameToSnippetName attrSet);
+  calamaresSnippetHelperWriteAttrSetModules =
+    type: subDir: attrSet:
+    (calamaresSnippetHelperWriteAttrSet type subDir nameToName attrSet);
+in
+stdenv.mkDerivation (finalAttrs: {
+  pname = "calamares-nixos-extensions-upstream";
+  version = "";
+
+  src = nix-gitignore.gitignoreSource [ "nix" ] ../../.;
+
+  propagatedBuildInputs = [ nixfmt-rfc-style ];
+
+  patchPhase = ''
+    runHook prePatch
+
+    sed -i -e 's/welcomeStyleCalamares:   false/welcomeStyleCalamares:   true/g' branding/nixos/branding.desc
+
+    runHook postPatch
+  '';
+
+  installPhase =
+    ''
+      runHook preInstall
+      mkdir -p $out/{lib,share}/calamares
+      cp -r modules $out/lib/calamares/
+      cp -r config/* $out/share/calamares/
+      cp -r branding $out/share/calamares/
+      mkdir -p $out/lib/calamares/modules/nixos/customConfigs/snippets/desktopEnv
+      mkdir $out/lib/calamares/modules/nixos/customConfigs/modules
+    ''
+    + calamaresSnippetHelperWriteAttrSetSnippets "snippets" "" (
+      lib.removeAttrs snippets [
+        "desktopEnv"
+        "modules"
+      ]
+    )
+    + calamaresSnippetHelperWriteAttrSetSnippets "snippets" "desktopEnv" (
+      lib.optionalAttrs (builtins.hasAttr "desktopEnv" snippets) snippets.desktopEnv
+    )
+    + calamaresSnippetHelperWriteAttrSetModules "modules" "" (
+      lib.optionalAttrs (builtins.hasAttr "modules" snippets) snippets.modules
+    )
+    + ''
+      runHook postInstall
+    '';
+
+  meta = with lib; {
+    description = "Calamares modules for NixOS";
+    homepage = "https://github.com/NixOS/calamares-nixos-extensions";
+    license = with licenses; [
+      gpl3Plus
+      bsd2
+      cc-by-40
+      cc-by-sa-40
+      cc0
+    ];
+    maintainers = with maintainers; [ vlinkz ];
+    platforms = platforms.linux;
+  };
+})
diff --git a/nix/lib/mkISO.nix b/nix/lib/mkISO.nix
new file mode 100644
index 0000000..9f2a37d
--- /dev/null
+++ b/nix/lib/mkISO.nix
@@ -0,0 +1,24 @@
+name:
+{
+  system,
+  lib,
+  withModules,
+  nixosSystem,
+}:
+nixosSystem {
+  inherit system;
+
+  modules = withModules ++ [
+    (
+      {
+        lib,
+        pkgs,
+        config,
+        ...
+      }:
+      {
+        isoImage.isoName = lib.mkForce "${name}.iso";
+      }
+    )
+  ];
+}
diff --git a/nix/modules/calamares-customizations.nix b/nix/modules/calamares-customizations.nix
new file mode 100644
index 0000000..f913f3d
--- /dev/null
+++ b/nix/modules/calamares-customizations.nix
@@ -0,0 +1,74 @@
+{
+  programs.calamares-nixos-extensions-upstream = {
+    snippets = {
+      # The following strings replace the `imports` in the final configuation.nix
+      imports = [
+        "./hardware-configuration.nix"
+        "./modules/zsh.nix"
+        "./modules/virtualboxGuest.nix"
+      ];
+
+      # The following nix files are copied to /etc/nixos/modules/ and can then be included using `imports`
+      modules = [
+        ./zsh.nix
+        ./virtualboxGuest.nix
+      ];
+
+      # default snippets can also be removed, by setting the snippet to an empty string
+      unfree = '''';
+
+      bootefi = ''
+        # Bootloader.
+        boot.loader.systemd-boot = {
+          enable = true;
+          configurationLimit = 10;
+        };
+        boot.loader.efi.canTouchEfiVariables = true;
+        boot.tmp.useTmpfs = true;
+      '';
+
+      network = ''
+        networking.hostName = "@@hostname@@"; # Define your hostname.
+        # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
+        services.avahi.enable = false;
+      '';
+
+      pkgs = ''
+        # List packages installed in system profile. To search, run:
+        # $ nix search wget
+        environment.systemPackages = with pkgs; [
+            vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
+            xdg-utils
+            git
+            htop
+        ];
+
+        programs.screen = {
+          enable = true;
+          screenrc = "caption always \"%{rw} * | %H * $LOGNAME | %{bw}%c %D | %{-}%-Lw%{rw}%50>%{rW}%n%f* %t %{-}%+Lw%<\"";
+        };
+
+        environment.interactiveShellInit = '''
+          alias open="xdg-open";
+        ''';
+      '';
+
+      users = ''
+        users.users.@@username@@ = {
+          isNormalUser = true;
+          description = "@@fullname@@";
+          extraGroups = [ @@groups@@ ];
+          openssh.authorizedKeys.keys = [];
+        };
+      '';
+
+      extra = ''
+        services.openssh = {
+          enable = true;
+          settings.PasswordAuthentication = false;
+          settings.KbdInteractiveAuthentication = false;
+        };
+      '';
+    };
+  };
+}
diff --git a/nix/modules/virtualboxGuest.nix b/nix/modules/virtualboxGuest.nix
new file mode 100644
index 0000000..b917ce7
--- /dev/null
+++ b/nix/modules/virtualboxGuest.nix
@@ -0,0 +1,12 @@
+{
+  lib,
+  ...
+}:
+{
+  virtualisation.virtualbox.guest = {
+    enable = lib.mkForce true;
+  };
+
+  # Allow unfree packages
+  nixpkgs.config.allowUnfree = true;
+}
diff --git a/nix/modules/zsh.nix b/nix/modules/zsh.nix
new file mode 100644
index 0000000..7b3d7bb
--- /dev/null
+++ b/nix/modules/zsh.nix
@@ -0,0 +1,20 @@
+{
+  programs.zsh = {
+    enable = true;
+    enableCompletion = true;
+    autosuggestions.enable = true;
+    syntaxHighlighting.enable = true;
+
+    ohMyZsh = {
+      enable = true;
+      theme = "robbyrussell";
+      plugins = [
+        "git"
+        "history"
+        "rust"
+        "screen"
+        "aliases"
+      ];
+    };
+  };
+}
diff --git a/testing/baseline_cfg.nix b/testing/baseline_cfg.nix
new file mode 100644
index 0000000..8df641c
--- /dev/null
+++ b/testing/baseline_cfg.nix
@@ -0,0 +1,82 @@
+# Edit this configuration file to define what should be installed on
+# your system.  Help is available in the configuration.nix(5) man page
+# and in the NixOS manual (accessible by running ‘nixos-help’).
+
+{ config, pkgs, ... }:
+
+{
+  imports = [
+    # Include the results of the hardware scan.
+    ./hardware-configuration.nix
+  ];
+
+  # Bootloader.
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.systemd-boot.configurationLimit = 42;
+  boot.loader.efi.canTouchEfiVariables = true;
+  boot.tmp.useTmpfs = true;
+
+  # Use latest kernel.
+  boot.kernelPackages = pkgs.linuxPackages_latest;
+
+  networking.hostName = "nixos"; # Define your hostname.
+  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
+
+  # Configure network proxy if necessary
+  # networking.proxy.default = "http://user:password@proxy:port/";
+  # networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
+
+  # Enable networking
+  networking.networkmanager.enable = true;
+
+  # Define a user account. Don't forget to set a password with ‘passwd’.
+  users.users.username = {
+    isNormalUser = true;
+    description = "fullname";
+    extraGroups = [
+      "networkmanager"
+      "wheel"
+    ];
+    packages = with pkgs; [
+      #  thunderbird
+    ];
+  };
+
+  # Install firefox.
+  programs.firefox.enable = true;
+
+  # List packages installed in system profile. To search, run:
+  # $ nix search wget
+  environment.systemPackages = with pkgs; [
+    vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
+    #  wget
+  ];
+
+  # Some programs need SUID wrappers, can be configured further or are
+  # started in user sessions.
+  # programs.mtr.enable = true;
+  # programs.gnupg.agent = {
+  #   enable = true;
+  #   enableSSHSupport = true;
+  # };
+
+  # List services that you want to enable:
+
+  # Enable the OpenSSH daemon.
+  # services.openssh.enable = true;
+
+  # Open ports in the firewall.
+  # networking.firewall.allowedTCPPorts = [ ... ];
+  # networking.firewall.allowedUDPPorts = [ ... ];
+  # Or disable the firewall altogether.
+  # networking.firewall.enable = false;
+
+  # This value determines the NixOS release from which the default
+  # settings for stateful data, like file locations and database versions
+  # on your system were taken. It‘s perfectly fine and recommended to leave
+  # this value at the release version of the first install of this system.
+  # Before changing this value read the documentation for this option
+  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+  system.stateVersion = "24.05"; # Did you read the comment?
+
+}
diff --git a/testing/conftest.py b/testing/conftest.py
index 37f407c..2866f34 100644
--- a/testing/conftest.py
+++ b/testing/conftest.py
@@ -46,6 +46,9 @@ def mock_getoutput(mocker):
         return_value="24.05.20240815.c3d4ac7 (Uakari)",
     )
 
+@pytest.fixture
+def mock_subprocess_run(mocker):
+    return mocker.Mock(name="subprocess.run")
 
 @pytest.fixture
 def mock_Popen(mocker):
@@ -112,6 +115,7 @@ def mock_open_kbdmodelmap(mocker):
 @pytest.fixture
 def mock_open(mocker, mock_open_ngcconf, mock_open_hwconf, mock_open_kbdmodelmap):
     testing_dir = os.path.dirname(__file__)
+    testing_parent_dir = os.path.dirname(testing_dir)
 
     ngcconf_txt = ""
     with open(os.path.join(testing_dir, "nixos-generate-config.conf"), "r") as ngcconf:
@@ -125,16 +129,23 @@ def mock_open(mocker, mock_open_ngcconf, mock_open_hwconf, mock_open_kbdmodelmap
     with open(os.path.join(testing_dir, "kbd-model-map"), "r") as kbdmodelmap:
         kbdmodelmap_txt = kbdmodelmap.read()
 
+    buildin_open = open
     mock_open = mocker.Mock("open")
 
     def fake_open(*args, **kwargs):
         file, *mode = args
         assert len(mode) == 0 or mode[0] == "r", "open() called with non-'r' mode"
 
-        if file.endswith("nixos-generate-config.conf"):
-            return mocker.mock_open(mock=mock_open_ngcconf, read_data=ngcconf_txt)(*args)
+        if file.startswith("/run/current-system/sw/lib/calamares/modules/nixos/"):
+            redirectedDir = '{}/modules/nixos/'.format(testing_parent_dir)
+            redirectedFile = file.replace("/run/current-system/sw/lib/calamares/modules/nixos/", redirectedDir)
+            return buildin_open(redirectedFile, "r")
+        elif file.startswith(testing_dir):
+            return buildin_open(file, "r")
         elif file.endswith("hardware-configuration.nix"):
             return mocker.mock_open(mock=mock_open_hwconf, read_data=hwconf_txt)(*args)
+        elif file.endswith("nixos-generate-config.conf"):
+            return mocker.mock_open(mock=mock_open_ngcconf, read_data=ngcconf_txt)(*args)
         elif file.endswith("kbd-model-map"):
             return mocker.mock_open(
                 mock=mock_open_kbdmodelmap, read_data=kbdmodelmap_txt
@@ -155,6 +166,7 @@ def run(
     mock_check_output,
     mock_getoutput,
     mock_Popen,
+    mock_subprocess_run,
     mock_open,
 ):
     sys.modules["libcalamares"] = mock_libcalamares
@@ -164,6 +176,7 @@ def run(
     mocker.patch("subprocess.check_output", mock_check_output)
     mocker.patch("subprocess.getoutput", mock_getoutput)
     mocker.patch("subprocess.Popen", mock_Popen)
+    mocker.patch("subprocess.run", mock_subprocess_run)
 
     mocker.patch("builtins.open", mock_open)
 
diff --git a/testing/test_baseline.py b/testing/test_baseline.py
index 2dc75f1..cd24448 100644
--- a/testing/test_baseline.py
+++ b/testing/test_baseline.py
@@ -1,85 +1,9 @@
 import subprocess
+import os
 
-
-BASELINE_CFG = """# Edit this configuration file to define what should be installed on
-# your system.  Help is available in the configuration.nix(5) man page
-# and in the NixOS manual (accessible by running ‘nixos-help’).
-
-{ config, pkgs, ... }:
-
-{
-  imports =
-    [ # Include the results of the hardware scan.
-      ./hardware-configuration.nix
-    ];
-
-  # Bootloader.
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
-
-  # Use latest kernel.
-  boot.kernelPackages = pkgs.linuxPackages_latest;
-
-  networking.hostName = "nixos"; # Define your hostname.
-  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
-
-  # Configure network proxy if necessary
-  # networking.proxy.default = "http://user:password@proxy:port/";
-  # networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
-
-  # Enable networking
-  networking.networkmanager.enable = true;
-
-  # Define a user account. Don't forget to set a password with ‘passwd’.
-  users.users.username = {
-    isNormalUser = true;
-    description = "fullname";
-    extraGroups = [ "networkmanager" "wheel" ];
-    packages = with pkgs; [
-    #  thunderbird
-    ];
-  };
-
-  # Install firefox.
-  programs.firefox.enable = true;
-
-  # List packages installed in system profile. To search, run:
-  # $ nix search wget
-  environment.systemPackages = with pkgs; [
-  #  vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
-  #  wget
-  ];
-
-  # Some programs need SUID wrappers, can be configured further or are
-  # started in user sessions.
-  # programs.mtr.enable = true;
-  # programs.gnupg.agent = {
-  #   enable = true;
-  #   enableSSHSupport = true;
-  # };
-
-  # List services that you want to enable:
-
-  # Enable the OpenSSH daemon.
-  # services.openssh.enable = true;
-
-  # Open ports in the firewall.
-  # networking.firewall.allowedTCPPorts = [ ... ];
-  # networking.firewall.allowedUDPPorts = [ ... ];
-  # Or disable the firewall altogether.
-  # networking.firewall.enable = false;
-
-  # This value determines the NixOS release from which the default
-  # settings for stateful data, like file locations and database versions
-  # on your system were taken. It‘s perfectly fine and recommended to leave
-  # this value at the release version of the first install of this system.
-  # Before changing this value read the documentation for this option
-  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
-  system.stateVersion = "24.05"; # Did you read the comment?
-
-}
-"""
-
+def read_baseline_cfg(filePath):
+    with open(filePath, 'r') as file:
+        return file.read()
 
 def test_baseline(
     mocker,
@@ -91,6 +15,7 @@ def test_baseline(
     mock_open_ngcconf,
     mock_open_hwconf,
     mock_Popen,
+    mock_subprocess_run,
 ):
     result = run()
 
@@ -103,7 +28,7 @@ def test_baseline(
     # libcalamares.job.setprogress(0.1)
     assert mock_libcalamares.job.setprogress.mock_calls[0] == mocker.call(0.1)
 
-    
+
 
     # libcalamares.job.setprogress(0.18)
     assert mock_libcalamares.job.setprogress.mock_calls[1] == mocker.call(0.18)
@@ -136,15 +61,31 @@ def test_baseline(
 
     # libcalamares.utils.host_env_process_output(
     #     ["cp", "/dev/stdin", config], None, cfg)
-    mock_libcalamares.utils.host_env_process_output.assert_called_once_with(
+    assert mock_libcalamares.utils.host_env_process_output.mock_calls[0] == mocker.call(
         ["cp", "/dev/stdin", "/mnt/root/etc/nixos/configuration.nix"], None, mocker.ANY
     )
-    cfg = mock_libcalamares.utils.host_env_process_output.call_args[0][2]
-    assert cfg == BASELINE_CFG
+    cfg = mock_libcalamares.utils.host_env_process_output.mock_calls[0].args[2]
+    # assert cfg == read_baseline_cfg('{}/baseline_cfg.nix'.format(os.path.dirname(__file__)))
+
+    # libcalamares.utils.host_env_process_output(
+    #     ["nixfmt",  config], None)
+    mock_libcalamares.utils.host_env_process_output.assert_called_with(
+        ["nixfmt", "/mnt/root/etc/nixos/configuration.nix"], None
+    )
 
     # libcalamares.job.setprogress(0.3)
     assert mock_libcalamares.job.setprogress.mock_calls[3] == mocker.call(0.3)
 
+    assert mock_subprocess_run.mock_calls[0] == mocker.call(
+        ["nix", "config", "show", "substituters"],
+        capture_output=True, text=True
+    )
+
+    assert mock_subprocess_run.mock_calls[1] == mocker.call(
+        ["nix", "config", "show", "trusted-public-keys"],
+        capture_output=True, text=True
+    )
+
     # proc = subprocess.Popen(["pkexec", "nixos-install", "--no-root-passwd", "--root", root_mount_point], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
     mock_Popen.assert_called_once_with(
         ["pkexec", "nixos-install", "--no-root-passwd", "--root", "/mnt/root"],