SolveCraft

Parametric 3D CAD; an open-source, clean-room reimplementation of Autodesk Fusion 360, built in pure Rust.

Sketch, constrain, and build solids with a parametric feature timeline. Change a dimension and watch your model rebuild. Run it on your desktop, in your browser, or let AI agents model through the built-in MCP server. Part of the storytold "craft" family.

An agent builds an electronics enclosure over MCP: sketches on faces, shell, a port cut, one screw boss patterned to four, then width 80 → 100 mm in the Parameters dialog and the timeline rebuilds. 3× speed; full video, script in examples/demo.

Documentation: the SolveCraft book (user guide, developer guide and command reference; sources in docs/book), and the web app to try it in the browser.

Status: early but usable for simple parts. 76 of 76 reference parts built in Fusion rebuild in SolveCraft with the same volume, area and topology (docs/oracle.md); command parity with Fusion's Design workspace is tracked in docs/parity.md. Open work and known bugs are in GitHub issues, and help is welcome: see CONTRIBUTING.md.

What works

• Sketches on the origin planes, offset planes or planar faces: lines, rectangles (2-point, 3-point, centre), circles (centre, 2-point, 3-point), arcs (3-point, centre), polygons, slots and points; construction geometry.
• Constraints and dimensions solved by our own solver (damped Gauss–Newton with degree-of-freedom analysis): coincident, horizontal/vertical, parallel, perpendicular, tangent, equal, concentric, collinear, midpoint, symmetry, fix; linear, aligned, horizontal, vertical, radius, diameter and angle dimensions driven by parameters. Over-constraining edits are rejected; fully constrained geometry turns black.
• Profiles found automatically, including regions split by lines and holes inside outlines.
• Features on a parametric timeline: extrude (one side, flipped, symmetric, two-sided, start offset; new body, join, cut, intersect), revolve, fillet and chamfer (straight convex edges), box, cylinder, sphere, torus, combine, move. The timeline rebuilds incrementally from the first changed feature; it can be rolled back, and features can be suppressed, renamed, edited and deleted.
• Parameters with unit-aware expressions (2 * width + 5 mm, angle / 2).
• Files: designs as JSON (.solvecraft), export to STEP (AP242 with body names, colours and components as assemblies; revolved faces as native planes, cylinders, cones, spheres and tori), IGES 5.3 (manifold solid B-reps with names and colours), 3MF, STL (binary/ASCII) and OBJ; 3MF, STL and OBJ import as mesh bodies (they render, measure, move and export; solid features need B-rep bodies); STEP import (AP203/AP214/AP242 solids, assemblies, units, names, colours) and IGES import (manifold solid B-reps, or trimmed and bounded surfaces sewn into solids) as a base feature that later features build on — open a .step/.stp/.igs/.iges file, insert one into a design, or drop it on the window (docs/step-import.md).
• Desktop app (egui + wgpu): toolbar with workspace tabs, browser, timeline, 3D viewport with view cube and navigation bar, sketch tools, feature dialogs, command palette, and a JSON-lines control channel so agents and tests can drive it.
• Headless CLI solvecraft-cli: run command scripts, measure (volume, area, centre of mass, face/edge/vertex counts), export, render PNG snapshots, replay Fusion oracle recipes.
• MCP server solvecraft-cli mcp: AI agents model, measure and look at parts headless or in the running app (see below).

Build and run

cargo run --release -p solvecraft -- --sample          # desktop app with a sample part
cargo run --release -p solvecraft-cli -- commands      # the command registry
cargo run --release -p solvecraft-cli -- run examples/bracket.json --out bracket.step
cargo run --release -p solvecraft-cli -- snapshot examples/bracket.json --out bracket.png
cargo run --release -p solvecraft -- part.step          # open a STEP file as a new design
cargo run --release -p solvecraft-cli -- eval part.step # measure an imported STEP file
cargo xtask ci                                          # fmt, clippy, tests, assets, layers, wasm

Windows builds: cargo xwin build --release --target x86_64-pc-windows-msvc -p solvecraft.

In the browser: cd apps/solvecraft-web && trunk build --release --public-url ./ (WebGPU, or WebGL2 with ?webgl; ?sample opens the sample part).

Scripts

A script is a JSON list of commands, the same ones the UI runs:

{"commands": [
  {"command": "sketch.create", "params": {"plane": "XY"}},
  {"command": "sketch.rectangle.two_point", "params": {"p0": [0, 0], "p1": [40, 30]}},
  {"command": "solid.extrude", "params": {"distance": 20}},
  {"command": "solid.fillet", "params": {"edges": [[0, 0, 10]], "radius": 3}}
]}

AI agents (MCP)

solvecraft-cli mcp is a Model Context Protocol server on stdio. Headless it runs its own design session; with --connect 127.0.0.1:PORT it drives the app started with solvecraft --control PORT, so you can watch the agent model. Tools: list_commands, execute, batch, inspect_design, measure, body_topology, set_parameter, screenshot (returns the image), export, undo, redo, new_design, open, save. Claude Code: claude mcp add solvecraft -- solvecraft-cli mcp. Details, client configuration and an example session: docs/mcp.md.

Architecture

Layer	Crates	Role
L0	geom	vectors, planes, profiles, meshes and their measures
L1	sketch, kernel, render	constraint solver and profiles; the B-rep kernel boundary (truck); view math and CPU rasterizer
L2	doc	parameters, expressions, the feature timeline and its incremental evaluation
L3	io	design files, STL/OBJ/STEP/3MF export, STEP and 3MF/STL import features
L4	engine	the session and the command registry (everything is a command)
L5	ui-egui, mcp	the swappable desktop front end; the MCP server (headless or bridged to the app)
apps	solvecraft, solvecraft-cli	desktop app, headless CLI

Contributing

See CONTRIBUTING.md: how to build and test, the code map, the clean-room and licence rules, and where help is wanted most.

Licence

MIT OR Apache-2.0, at your option. SolveCraft is not affiliated with Autodesk; Fusion is a trademark of Autodesk, Inc.