Pentos Slicer

Pentos Slicer is a small Python 3.13 web UI for preparing a model, placing interactive slice planes, exporting oriented STL chunks, running PrusaSlicer, and merging the generated G-code with Pentos A/B transition moves.

The app uses Viser for the browser-based 3D interface and trimesh for model loading and geometry operations.

Demo

Place and orient interactive slice planes	Preview the generated multi-part toolpath

Requirements

• Python 3.13
• uv
• prusa-slicer available on PATH when running the full slicing pipeline

Install the Python environment:

uv sync

Run

Start the local Viser app:

uv run python main.py

For development, restart it automatically whenever a Python file changes:

./dev.sh

Open the URL printed in the terminal, usually:

http://localhost:8080

Or build and run it with Docker:

docker build -t pentos-slicer .
docker run --rm -p 8080:8080 pentos-slicer

At most two models are sliced concurrently by default. Set MAX_CONCURRENT_SLICES to a positive integer to change that limit. Uploads are limited to 50 MB by default. Set MAX_UPLOAD_SIZE_MB to a positive integer to change that limit.

Basic Workflow

1. Upload a model (.stl, .3mf, .obj, or .ply).
2. Add one or more slice planes.
3. Move or rotate planes with the viewport gizmo or GUI controls.
4. Click Slice.
5. The app switches to a preview shell showing the generated G-code path.
6. Click Back to Setup to return to the model and plane controls.

Sample models are available in samples/.

Machine Configuration

The Machine panel imports and exports versioned .json machine profiles. The active profile is saved in the browser and restored on future visits. Profiles contain machine geometry; the PrusaSlicer profile remains in pentos_config.ini.

{
  "format": "pentos-machine",
  "version": 1,
  "name": "My Pentos",
  "build_volume_mm": [90, 90, 90],
  "machine_plate_center_mm": [113, 52, 0],
  "rotation_center_machine_mm": [112, 51, 2]
}

machine_plate_center_mm and rotation_center_machine_mm are in machine coordinates. Pentos derives the slicer-local plate center, machine offset, and local rotation center from these values.

Project Layout

• main.py starts the Viser server and mounts the application controller.
• models/ stores shared application state, plane snapshots, and preview data.
• controllers/ coordinates setup, preview, slicing, export, and navigation.
• views/ contains the Viser UI, scene rendering, plane editor, and theme.
• services/ contains model/project I/O, slicing, preview parsing, and Pentos-specific G-code workflows.
• gcode_tools/ contains reusable G-code parsing and transformation utilities.
• machine.py stores machine geometry constants.
• samples/ contains example models and saved Pentos scenes.

Generated runtime files are written to uploaded_models/, temp/, and output/. These are local outputs and should not be committed.

App Structure

AppController is the composition root. It creates the shared AppState, services, screen controllers, and views:

• Models hold data independently of Viser and external processes.
• Controllers mutate application state and coordinate services.
• Services perform geometry, filesystem, slicing, parsing, and network work.
• Views create Viser handles, render state, and forward user actions.

Plane edits update controller-owned snapshots as they happen. Runtime plane IDs are not included in version-1 .pentos manifests, so existing scenes remain compatible.

Development Checks

Format touched Python files:

uv run ruff format .

Run tests and a quick syntax check:

uv run pytest
uv run python -m compileall .

For visible UI changes, run the app, load a sample model, add a plane, and exercise the setup-to-preview flow.

License

Pentos is licensed under the GNU General Public License v3.0.