Millwright

The open-source AI machinist for SolidWorks — talk to your CAD.

Quick Start · How it works · AI providers · Architecture · Contributing · 中文

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Describe what you want in plain language — "sketch a 50×30 rectangle on the front plane and extrude it 20 mm" — and Millwright drives SolidWorks to do it. The AI plans the work, calls real modeling tools one step at a time, reads structured results back, and corrects itself as it goes.

You choose the AI backend. Claude, GPT-4o, DeepSeek, Kimi, MiniMax, Qwen, or a local Ollama model — anything speaking the Anthropic or OpenAI-compatible protocol. The code is open; you pay only your own API usage.

Existing CAD AI tools lock you into one provider at $16–417/mo. Millwright is free and provider-agnostic.

	Typical CAD AI SaaS	Millwright
AI backend	Fixed by plan	Any model you choose
Pricing	$16–417 / month	Free (you bring your own API key)
Source	Closed	Open (Apache-2.0)
Automation	Prompt → one-shot script	Agentic tool loop with self-correction
Visual feedback	—	Screenshots the viewport & reasons over it

Features

• Natural language → real modeling. English or Chinese in; sketches, features, assemblies, and exports out.
• Agentic tool loop. The model calls structured, single-purpose tools (create_sketch, extrude, chamfer, mass_properties, …), receives JSON results, and chains multiple steps to finish a task — recovering from errors instead of failing silently.
• Native function calling. Tools are injected into the model via the standard tools API, not stuffed into a prompt. One source of truth — the tools describe themselves.
• Visual understanding. The agent can reorient, rotate, and screenshot the model, then analyze it — either through a dedicated vision model (image→text) or by feeding the image straight to a multimodal main model.
• Resident execution engine. A persistent Python sidecar drives the SolidWorks COM API directly (via pywin32), holding one connection across many steps.
• Safety first. Per-language script validation, automatic pre-execution backup, and a confirmation gate before any destructive operation.
• Developer-friendly. 167 unit tests, typed IPC boundary, and a SKIP_SW_CONNECT mode for UI-only development without SolidWorks.

Quick Start

Install

1. Download the installer from Releases and run it.
2. Install the sidecar runtime (drives SolidWorks):

   pip install pywin32 pillow

   Without Python, the app still runs and falls back to the legacy VBScript engine — but you lose structured results and visual understanding. Installing Python is strongly recommended.

From source

git clone https://github.com/raylanlin/millwright.git
cd millwright
npm install
npm run dev

UI-only development without SolidWorks: set SKIP_SW_CONNECT=true.

Configure

1. Start SolidWorks, then launch Millwright.
2. Open ⚙️ Settings → pick a protocol → enter Base URL, API key, and model → Save.
3. (Optional) Enable Vision: either toggle "main model supports images" or configure a separate vision model.

Supported AI providers

Provider	Protocol	Base URL	Suggested model
DeepSeek	OpenAI-compatible	https://api.deepseek.com	deepseek-v4-pro
Kimi / Moonshot	OpenAI-compatible	https://api.moonshot.cn/v1	kimi-k3
MiniMax	OpenAI-compatible	https://api.minimaxi.com/v1	minimax-m3
Anthropic	Anthropic	https://api.anthropic.com	claude-sonnet-4
OpenAI	OpenAI	https://api.openai.com/v1	gpt-4o
Alibaba Bailian (Qwen)	OpenAI-compatible	https://dashscope.aliyuncs.com/compatible-mode/v1	qwen-max
SiliconFlow	OpenAI-compatible	https://api.siliconflow.cn/v1	—
Ollama (local)	OpenAI-compatible	http://localhost:11434/v1	—

Agentic tool calling requires a model that supports function calling. DeepSeek, Kimi K3, and MiniMax M3 are first-class targets.

Examples

You: Sketch a 50×30 rectangle on the front plane and extrude it 20 mm.
AI:  create_sketch(front) → sketch_rectangle(50,30) → extrude(20)  ✓  part created

You: How heavy is this part, and what's its bounding box?
AI:  mass_properties → bounding_box  ✓  0.42 kg · 50 × 30 × 20 mm

You: Look at it from isometric — do the proportions look right?
AI:  set_view_orientation(isometric) → analyze_view("are the proportions balanced?")  ✓

You: Set every fillet in the model to 3 mm.
AI:  fillet_all(3)  → confirm? → ✓  6 fillets updated

How it works

Renderer (React UI)
      │  IPC
Main process (Electron / Node)
      │  agent loop  ──  native function-calling tools injected into the model
      │      ├─ tool source & execution = sidecar (structured JSON in/out)
      │      └─ analyze_view ─┬─ dedicated vision model (image→text)
      │                       └─ or multimodal main model (image fed directly)
      │  JSON-RPC over stdio
Python sidecar (resident)  ──  pywin32 → SolidWorks COM API
      │
SolidWorks

• Structured, observable tools. Every tool returns { ok, data | error } JSON, so the model can read the real state (feature tree, dimensions, mass, interferences) and plan the next step.
• Legacy path retained. If the Python sidecar can't start, the app automatically falls back to the original VBScript engine so nothing hard-breaks.
• Zero SDK dependency for LLM access: native fetch + a hand-written SSE parser.

See docs/ARCHITECTURE.md for the full design.

Requirements

• Windows 10/11 (64-bit)
• SolidWorks 2017+
• Python 3.9+ with pywin32 and pillow (for the sidecar)
• Node.js 20+ (development only)

Documentation

Doc	What's inside
Architecture	System design, modules, data flow
User Guide	Install, configure, FAQ
Development	Code layout, conventions, testing
API Reference	LLM interfaces, tool catalog
Contributing	How to contribute
Verification backlog	Multi-parameter APIs pending macro-recorder verification
Changelog	Version history
Security	Security policy & disclosure

Contributing

Contributions welcome — see CONTRIBUTING.md. We especially value:

• 🧪 Test reports from real SolidWorks environments (and macro-recorder verification of the pending APIs)
• 🔨 New sidecar tools (sidecar/sw_agent/tools/)
• 🎨 UI/UX improvements
• 🌐 Adapters for other CAD (Inventor, CATIA, NX) and MCP server integration
• 📝 Documentation & translations

Roadmap

• v0.1 — MVP (Electron + LLM + COM + tools)
• v0.2 — Stable base, CI, docs
• v0.2.4 — Python sidecar, agentic tool loop, visual understanding, Apache-2.0 open source ← current
• v0.3 — Full tool coverage, macro-verified parameters, streaming tool calls
• v1.0 — MCP server, multi-CAD support

Name

Millwright (n.) — a skilled tradesperson who installs, maintains, and operates machinery. That's the role this tool plays: the AI machinist standing at your SolidWorks bench.

License

Apache-2.0 — permissive, with an explicit patent grant. Free for commercial use.

Acknowledgments

• SolidWorks COM API reference: CodeStack
• Inspiration: Cursor, Claude Code

_{SolidWorks is a registered trademark of Dassault Systèmes. Millwright is an independent open-source project and is not affiliated with or endorsed by Dassault Systèmes.}