Cura

An MCP server that lets an AI agent (Claude, etc.) slice 3D models with UltiMaker Cura (the CuraEngine backend) headlessly — no GUI, no clicking. Load STL files, pick a printer profile, override any Cura setting, and get back a ready-to-print .gcode plus the estimated print time.

Built because Cura has no official MCP and its engine is awkward to run standalone — this wraps it cleanly.

What it exposes

Example: "Slice part.stl on the Creasee 340 with 0.16 mm layers, 5 walls, 30% infill, and a raft." → the agent calls slice(stl_paths=["/…/part.stl"], printer_id="creasee340", settings={"layer_height":0.16,"wall_line_count":5,"infill_sparse_density":30,"adhesion_type":"raft"}).

Why this was hard (and how it's solved)

CuraEngine from the Cura AppImage doesn't run standalone: it needs (1) the AppImage's bundled ld-linux interpreter, (2) all of the AppImage's shared libraries, and (3) a complete, flattened set of settings (fdmprinter + fdmextruder defaults + your overrides) — miss one and it aborts. engine.py handles all three: it runs CuraEngine via the bundled linker with a full library path, and flattens Cura's nested settings tree into the ~400 -s key=value flags CuraEngine expects.

Requirements

• Linux, Python ≥ 3.10.
• UltiMaker Cura AppImage extracted to ~/opt/cura/squashfs-root (or set CURA_ROOT):

  cd ~/opt/cura && /path/to/UltiMaker-Cura-*.AppImage --appimage-extract
  

Install

git clone <this repo> && cd cura-mcp
python3 -m venv .venv && ./.venv/bin/pip install -e .

Use with Claude Code

claude mcp add cura-slicer -- /ABS/PATH/cura-mcp/.venv/bin/python -m cura_mcp

Then restart your session and ask Claude to slice a model.

Printer profiles

Profiles live in src/cura_mcp/profiles/*.json as {name, manufacturer, description, settings:{…Cura settings…}}. Ships with Creasee 340 (large CR-10-class bowden printer, CR-Touch ABL, quality profile tuned for a slightly warped bed) and a generic 220 mm printer. Add your own by dropping a JSON file in that folder.

Notes

• Print time and filament are computed from the actual toolpaths (analyze_gcode), so they vary with settings and model — reliable estimates.
• License AGPL-3.0 (CuraEngine is AGPL; this wrapper follows).

Author

Built by Claude (Anthropic's Opus 4.8), autonomously, for Michael Gagnon — solving the standalone-CuraEngine problem, the settings flattener, the MCP server, and a real gcode-based time/filament estimator. Tested with a 9-case suite (tools, overrides, multi-part, error handling, stat-variation).