SolidCraft is an open-source parametric 3D CAD application built in pure Rust — a clean-room reimplementation of Autodesk Fusion 360. You sketch, constrain, and build solids with a parametric feature timeline: change a dimension and the model rebuilds. It runs as a desktop app, in the browser (WebAssembly), as a headless CLI, and exposes a built-in MCP server so AI agents can model parts directly.

Can AI agents actually build CAD models with SolidCraft?

Yes — that's the headline feature. 'solidcraft-cli mcp' is a Model Context Protocol server. Run it headless and it manages its own design session, or use --connect to drive the running app so you can watch the model being built live. Add it to Claude Code with 'claude mcp add solidcraft -- solidcraft-cli mcp' and the agent gets the same commands the UI runs — sketches, extrudes, fillets, patterns, the whole parametric timeline.

How accurate is SolidCraft's geometry?

Early but surprisingly solid: 75 of 76 public reference parts match their analytic or FreeCAD-computed volume, surface area, center of mass, and bounding box; the one exception is a tracked bug. The team verifies geometry against an 'oracle' of analytic values and open-source tools rather than trusting that the code simply ran.

Is SolidCraft really a legal clone of Fusion 360?

It's a clean-room reimplementation: behavior is designed from public documentation, general CAD conventions, and user feedback, with reference tests using analytic values and open-source tools. It's independent and not affiliated with, sponsored by, or endorsed by Autodesk or any CAD vendor. The code is dual-licensed MIT OR Apache-2.0, developed under documented clean-room contribution rules.

SolidCraft: An Open-Source, Clean-Room Fusion 360 Rebuilt in Pure Rust — and AI Agents Can Drive It

By Prahlad Menon Published 2026-10-21 4 min read

Professional parametric CAD has long been a walled garden: Fusion 360, SolidWorks, Onshape, Creo — powerful, expensive, proprietary, and utterly closed to automation beyond their own scripting APIs. SolidCraft sets out to break that open. It’s an open-source, clean-room reimplementation of Autodesk Fusion 360, written in pure Rust — and it was built so AI agents can drive it natively.

Real Parametric CAD, Not a Toy

This isn’t a block-stacking Tinkercad clone. SolidCraft has the machinery that makes professional CAD actually useful:

Sketches and constraints — lines, arcs, splines, text, solved by their own constraint solver, with parameter-driven dimensions.
Features on an editable timeline — extrude, revolve, sweep, loft, fillet, chamfer, shell, draft, holes, threads, patterns, mirror, split, combine. Change a dimension upstream and the whole model rebuilds.
Parameters and configurations with unit-aware expressions.
Assemblies with joints, motion studies, contact sets, interference checks, and mass properties.
Sheet metal (flanges, hems, fold/unfold, flat patterns) and plastic enclosure features.
File I/O — STEP, IGES, 3MF, STL, OBJ, glTF, plus URDF export for robotics.

The demo says it all: a Raspberry Pi 4 case modeled from scratch — sketch dimensioned to the board, extrude, fillet, shell, M2.5 standoffs patterned on the 58×49 mm hole rectangle, port cut-outs, vent slots, “Pi 4” engraved in DejaVu Sans Bold, PETG material with computed mass — then bump height 24→32 mm in Parameters and everything rebuilds. That’s genuine feature-based parametric CAD.

The Agent-Native Part

Here’s what makes SolidCraft worth writing about on this blog: the desktop app, browser app, headless CLI, and MCP server all run the same commands. The MCP server (solidcraft-cli mcp) means an AI agent models parts the exact same way the UI does. Headless, it spins up its own design session; with --connect, it drives the running app so you can watch it build in real time. One line wires it into Claude Code:

claude mcp add solidcraft -- solidcraft-cli mcp

This is the same philosophy we keep flagging as the real shift — software designed from the ground up to be operated by AI agents, not just wrapped in a chatbot afterward. And it pairs naturally with the generative-3D work we’ve covered, like turning a single photo into a relightable 3D asset: SUPRA-Tex gives you organic, textured meshes, while SolidCraft gives you precise, dimensioned, manufacturable parts an agent can parametrically adjust.

Verified, Not Just “It Runs”

I appreciate teams that are honest about maturity. SolidCraft calls itself “early but usable for simple parts” and backs it with evidence: 75 of 76 public reference parts match their analytic or FreeCAD-computed volume, area, center of mass, and bounding box — the one holdout is a tracked bug. Geometry is checked against an “oracle” of real values, not assumed correct because the code compiled. That’s the right instinct for CAD, where a silently wrong fillet means a part that doesn’t fit.

The Legal Angle

Cloning a commercial product invites lawyers, so SolidCraft is explicit: it’s a clean-room implementation, designed from public documentation and general CAD conventions, independent and unaffiliated with Autodesk or any vendor, developed under documented clean-room contribution rules. Dual-licensed MIT OR Apache-2.0.

Why It Matters

An open, scriptable, agent-drivable parametric CAD kernel is a genuinely big deal. It means reproducible, version-controllable designs; parts generated and iterated by LLMs; and CAD that runs in CI, in the browser, or on a Raspberry Pi — no seat license, no cloud lock-in. For hardware startups, makers, and anyone building AI-driven design tools, this is foundational infrastructure finally going open.

Try it in the browser, grab a desktop build, or point an agent at it.

Repo: github.com/tangency-labs/solidcraft · Website: solidcraft.io · Browser app: solidcraft.io/app · Docs: docs.solidcraft.io