build123d
Apache-2.0 Python CAD-as-code on Open Cascade — the library under text-to-cad
Python / CAD · Apache-2.0 · 3.5k
Reviewed 2026-10-06 · last push 2026-10-18 · repo checked 2026-10-19
What's Good
Apache-2.0 (gumyr/build123d). Free path: `pip install build123d` (or uv). Fully Pythonic API over Open Cascade for 2D/3D solids, exports for manufacturing, docs and cheat sheet at build123d.readthedocs.io. This is the modeling engine the text-to-cad agent plugin wraps — use build123d when you want the raw library in your own scripts, notebooks, or services. ★~3.3k.
The Catch
Raw modeling library: no agent harness, no MCP, no viewer — pair with text-to-cad when an agent should drive CAD. Heavy Open Cascade / OCP install (native wheels, first install is large and platform-sensitive). Vs FreeCAD/CadQuery: CadQuery is the older Python OCCT layer; build123d is the newer ergonomic API many agent tools standardize on. Geometric correctness still needs a human tolerance pass before you cut metal.
Verdict
Apache-2.0 Python CAD library when you need code-first solids — free via pip; for the agent seat see text-to-cad.
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