Agent skill · software engineering · aradotso
text-to-cad-harness
Open source harness for generating 3D CAD models from text using AI coding agents with build123d/OpenCascade, exporting STEP/STL/URDF, and previewing in a local CAD Explorer viewer.
Why this skill is useful
Adds executable scripts for generating and exporting 3D CAD models from text descriptions using build123d, which the AI cannot generate on its own.
What it needs
Requires npm, python installed locally. About 5k tokens when loaded. Last updated 2026-07-09. 70 stars on the source repository.
What this skill does
⚙ Text-to-CAD Harness Skill by ara.so — Daily 2026 Skills collection. An open source harness that lets AI coding agents (Claude Code, Codex, Cursor, etc.) generate, export, and preview 3D CAD models from natural language descriptions. Models are written in Python using build123d on top of OpenCascade (OCP), exported to STEP/STL/DXF/GLB/URDF, and inspected in a local React/Vite CAD Explorer viewer. --- How It Works models/ — Source-controlled Python CAD files (build123d scripts) skills/cad/ — Bundled CAD skill (STEP, STL, DXF, GLB, snapshots, @cad[...] references) skills/urdf/ — Bundled URDF skill (robot links, joints, validation) viewer/ — Local React/Vite CAD Explorer (no backend required) --- Installation 1. Clone the repo 2. Set up Python CAD environment Requires Python 3.11+. The requirements-cad.txt pins build123d, OCP, and all geometry dependencies. 3. Install viewer dependencies 4. Start the CAD Explorer Open http://localhost:4178 to browse generated models. --- Project Structure --- Writing CAD Models (build123d) All models live under models/ as Python scripts using build123d. Basic Part Example Running a Model to Generate Artifacts Parametric Part with Variables Assembly Example --- Exporting Formats From within any models/.py script, use build123d export functions: --- URDF Robot Descriptions The bundled URDF skill generates robot description files. See skills/urdf/SKILL.md for full docs. URDF Example Structure Minimal URDF Output Pattern --- CAD Explorer Viewer The local viewer reads exported files from models/ and renders them in browser using WebAssembly (WASM). Viewer Commands Viewer Features Browse all models in models/ directory Inspect STEP/GLB geometry in 3D Copy @cad[...] geometry references for agent follow-up edits Quick snapshot renders for iteration review --- @cad[...] Geometry References After generating a model, the viewer provides stable @cad[...] handles. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills aradotso/text-to-cad-harness