3BCAD is an open-source parametric 3D CAD software, fully written in Rust, running on Windows, macOS, and Linux. You can create constrained 2D sketches, turn them into 3D solids using extrude, revolve, sweep, loft, fillet, shell, threaded holes, patterns…, and all dimensions are still editable: change one number, and the entire detail rebuilds itself.

Problem addressed: professional parametric CAD software is often expensive, heavy, and tied to a single operating system, while free tools lack the detailed preparation steps for 3D printing. 3BCAD combines design and printing preparation in one place, free and open-source.

Main features:

• 2D sketching with constraints and dimensions, Levenberg–Marquardt solver; feature history with rollback, suppress, reorder, undo/redo.
• 3D Print Studio: view details on the print bed of printers (Bambu Lab, Prusa, Creality, Voron), color areas needing support and where it is too thin, Lay Flat one side down on the bed, add fit slots (press/slip/loose) for FDM, resin, powder; export 3MF and send directly to OrcaSlicer, Bambu Studio, PrusaSlicer.
• Assembly (available from v0.7): mating between faces, dragging parts with the mouse according to constraints, collision checking with volume, exploded view, bill of materials (BOM) exported as CSV, exporting multiple details in STEP and 3MF.
• 2D technical drawing (available from v0.8): ISO and ANSI formats, auto-filled title block, standard projections and auxiliary views with hidden lines, sections, callouts, dimensions taken from the model or measured on the view; export PDFs to scale, SVG, and DXF with separate layers.
• Import STEP, STL, 3MF, OBJ, DXF; export STL, 3MF, STEP, DXF; automatically save and recover when the software crashes unexpectedly.

Who should use it: makers and 3D printers who want to design accurate mechanical details (supports, enclosures, joints, gears…) instead of modeling meshes; students and mechanical engineers needing a lightweight, free parametric CAD tool; programmers interested in 3D geometry, constraint solvers, and GPU graphics with Rust.

How to get started: visit the Releases page on GitHub, download the version for Windows, macOS, or Linux, unzip, and run it (no installation required); from version 0.8, the app notifies you when a new version is available, and updates with one click. Or build from the source: install Rust and then run cargo run --release. The README provides step-by-step instructions for creating your first detailed part, printing it, assembling, and drawing.

What sets it apart: every component — B-Rep geometry kernel (truck), constraint solver, feature history, GPU viewport, file I/O — is built in memory-safe Rust, eliminating the need for C++ toolchains, with a single build command to run. The 3D printing tool is available directly within CAD instead of needing to switch between multiple software. The .3bcad file is readable JSON, easy to manage with Git.

The project is in early preview stage (v0.8; next up are variables, equations, and configurations for v0.9, see the Roadmap tab), licensed under MIT or Apache-2.0, developed by 3 Bugs Studio. We welcome feedback, bug reports, and contributions from the community!