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build123d MCP servers and AI agent skills

build123d has no MCP server from its own maintainers, but several community projects give agents a build123d session: a server that keeps a live session for step-by-step modelling and measuring, a Docker renderer, a CAD command line that versions every run, and a skill for testing mechanisms built from several parts. All of them work on Python files and need no CAD program open. They suit 3D-printed parts and small mechanisms more than large assemblies.

  • No official Open source server yet.
  • 3 MCP servers and 1 agent skill listed.
Open source3 servers · 1 skillChecked 4 Nov 2026

Integrations for build123d

Community and commercial servers

MCP serverCommunity

agentcadby James Dillard

A CAD command line and MCP server that runs build123d (or CadQuery) scripts, renders, measures and diffs them.

LocalCan modify models199· updated 1 day ago
MCP serverCommunity

build123d-mcpby pzfreo

A build123d session server that lets the assistant model step by step, render, measure and export.

LocalCan modify models141· updated 3 weeks ago
MCP serverCommunity

CAD Agentby Svetlana DAO LLC

A Docker container that runs build123d code, renders it with VTK and returns images over HTTP or MCP.

LocalCan modify models57· updated 9 months ago

Agent skills

SkillCommunity

CAD Khanaby cyberchitta

A skill and CLI that turn build123d parts into tested mechanisms with joints, motion and interference claims.

19· updated 11 days ago

Listings are sorted by origin, then by recent activity. GitHub data is refreshed nightly. Nothing here is ranked.

How AI connects to build123d

An MCP server or skill can only do what build123d lets programs do. build123d exposes 1 automation interface:

  • build123d Python library (Python): build123d is a Python framework for parametric BREP modelling on the Open Cascade kernel. It offers a builder mode and an algebra mode, where parts are combined with operators such as += and *. Agents can work in either, but a persistent session helps: the build123d-mcp server lets the assistant add one feature, measure it and render it before moving on, instead of writing a whole script blind. Documentation

What Open source offers

build123d is an open-source project maintained on GitHub under gumyr. Its documentation, checked on 4 November 2026, does not mention AI assistants, LLMs or MCP, and the maintainers have not published an MCP server. The integrations listed here are independent community projects; one cites results on the public CADGenBench leaderboard, which compares AI CAD generation.

Checked 4 Nov 2026. Sources: build123d documentation, pzfreo/build123d-mcp README (CADGenBench results)

What you can do with build123d and AI

  • Build a part one feature at a time in a persistent build123d session, measuring volume, bounding box and centre of mass after each step.
  • Find holes, bosses and countersinks in a model and check printability and fit against an imported STEP or STL.
  • Compose parts into a mechanism with joints and motion, then assert claims such as no interference or a minimum wall, and fix the design until they pass.
  • Produce 2D engineering drawing previews and export STEP, STL, DXF or SVG.
  • Keep every script run as a labelled version and diff two versions of a part.

Taken from the listings' own documentation. Check each listing for exactly what it supports.

Installing

The listings here document setup for Claude Code, Claude Desktop, Cline, Codex, Continue, Cursor, VS Code and Windsurf. Install steps, copied from each project's own documentation, are on each listing's page. Most build123d integrations run on your own computer next to build123d, so you need build123d installed and licensed on the same machine unless the listing says otherwise.

Related tools

CadQueryOpen source3 servers · 1 skillOpenSCADOpen source2 servers · 1 skillFreeCADOpen source8 serversBlender / Bonsai (IFC)Blender Foundation4 servers · 1 skillMastercamCNC Software1 server

Questions

Is there an official build123d MCP server?

No. The build123d maintainers haven't published one. The listed servers and skill are community projects that run build123d code locally or in a container.

How does an AI agent use build123d?

The agent writes Python that calls build123d, and a server runs it and sends back measurements, renders and exported files. Servers with a persistent session let the agent build and check a part in small steps instead of rerunning a whole script.

Do I need a CAD licence for build123d?

No. build123d is an open-source Python library, so these integrations run without any commercial CAD software. You only need Python (3.11 to 3.14 for build123d-mcp, 3.13 for CAD Khana) or Docker for the containerised renderer.

Is build123d or CadQuery better for agents?

Neither is ranked here. They are separate Python projects written in different styles; one command-line tool runs build123d by default and keeps CadQuery as an option, so you can try both on the same task.

AI-generated models, drawings and results must be checked by a qualified engineer before use.

Sources (checked 4 Nov 2026): build123d documentation · pzfreo/build123d-mcp README · cyberchitta/cad-khana README · build123d product page

build123d is developed by its own project (Open source). Tresca is independent and not affiliated with or endorsed by the build123d project.