A CAM toolchain for making printed circuit boards at home — one tool for the whole cycle, from fab package to finished board.
Cuprum takes a Gerber/Excellon fab job and drives the machines on your bench to produce a real PCB. It treats fabrication as a set of processes — each one a (layer, machine, action) — and ties them together with shared fiducials so the steps register against each other automatically.
The first process to land is UV photolithography: exposing the copper artwork through a high-resolution UV LCD (Cuprum currently drives an Elegoo Saturn 4 Ultra 16K). Drilling and edge-cut routing on a CNC are next on the roadmap.
Status: early, actively developed. The UV exposure pipeline works end-to-end; the rest of the CAM features (drill, edge-cut routing, fiducial registration) are on the roadmap. See
docs/VISION.md.
Cuprum plays to each tool's strengths rather than forcing one machine to do everything:
- Light for copper. Exposing traces and pads is parallel — the entire artwork lands in a single flash (~90 s) regardless of trace density or how many boards are on the bed. A modern UV LCD also resolves a fine pitch (a 16K screen is ≈14×19 µm per pixel), finer than a cheap CNC mill can route.
- CNC for the rest. Use a mill only where light can't help: drilling holes and cutting the board outline.
- Fiducials tie it together. One set of registration marks links every process, so exposure → drilling and double-sided alignment become automatic.
| Component | Crate / dir | What it does |
|---|---|---|
| Core library | crates/cuprum-core | Gerber parsing, rasterization (tiny-skia), composition onto the 15120×6230 screen, .goo encoding, and the SDCP protocol (discover / upload / expose). |
| CLI | crates/cuprum-cli | cuprum binary: a headless toolbox over the same engine as the GUI — info, render (PNG), svg, 3d (glTF/STL/OBJ), check (DFM metrics + gate), each over a gerber file/dir or a .cuprum project. |
| Project model | crates/cuprum-project | The self-contained .cuprum project container and the recents catalog. |
| Desktop UI | cuprum-ui | Tauri 2 + React app: native-sharp preview, CAD-style navigation (zoom-to-cursor, pan, grid, snapping), multi-select, alignment/auto-layout, 3D board view, and one-click exposure. |
Before you burn a board, Cuprum tells you whether it can actually be made on your bench. It reads the fab package and measures the real manufacturing facts — then judges each one against an editable machine capability profile (min trace, min space, drill bits, panel size, …). Measurement lives in the Rust core; the judgement lives in the UI, so editing a threshold re-evaluates instantly without re-crunching geometry. The whole pass runs off the preview's critical path, so the board stays interactive while it computes.
Each check resolves to ok / warn / block (plus advisory info for cosmetic layers), and they roll up into a single verdict badge. Located issues are drawn straight onto the board as side-aware markers — a bottom-side short isn't drawn while you're looking at the top — so you can step through every offending feature instead of hunting for it.
What it currently checks:
- Board size — fits the panel/work area (optionally rotated 90°), and warns on an open (non-stitched) outline where the measured size is only an estimate.
- Layer stack — copper layer count and unsupported inner layers.
- Minimum trace width — narrowest routed copper, per side, artefact-filtered.
- Copper-to-copper clearance — true geometric spacing (shorts).
- Copper slivers — features narrower than the trace minimum.
- Annular ring — plated-hole pad rings, including holes with no pad at all.
- Drilling — smallest hole vs. your floor, and tool sizes that don't snap to any available CNC bit.
- Vias — small holes that would need plating you don't have at home.
- Solder-mask dams — web width between adjacent mask openings.
- Silk line width — legend strokes too thin to render, judged per side.
- Overshoot & slots — features poking past the board edge, routed slots.
Defaults are tuned for an Elegoo Saturn 4 Ultra 16K + a hobby CNC; every threshold is editable on the Settings page.
- Rust (stable, edition 2021)
- For the desktop UI: Node.js, pnpm, and the Tauri 2 prerequisites for your platform.
# Build the whole workspace
cargo build --release
# Summarise a gerber file/dir or a .cuprum project
cargo run -p cuprum-cli -- info path/to/gerbers/
# Composite colour PNG / SVG preview
cargo run -p cuprum-cli -- render path/to/gerbers/ -o board.png
cargo run -p cuprum-cli -- svg path/to/board.cuprum -o board.svg
# Export the 3D board mesh (glTF/STL/OBJ)
cargo run -p cuprum-cli -- 3d path/to/gerbers/ -o board.glb --format gltf
# Measure DFM facts and gate against manufacturability limits (exit 2 on fail)
cargo run -p cuprum-cli -- check path/to/board.cuprum
cargo run -p cuprum-cli -- --json check path/to/gerbers/Each command accepts a gerber file, a directory of gerbers, or a .cuprum project.
Run cargo run -p cuprum-cli -- --help for the full command list.
Driving the printer (discover / upload / expose) currently lives in the desktop app; a headless hardware workflow on the project model is planned.
cd cuprum-ui
pnpm install
pnpm tauri devThe app updates itself: it checks GitHub Releases on launch and offers a signed in-app update when a newer version is available.
On macOS the release bundles are not yet signed with an Apple Developer ID, so the first launch of a freshly downloaded build may show an "unidentified developer" warning. Bypass it once: right-click the app → Open → Open, or strip the download quarantine flag:
xattr -dr com.apple.quarantine /Applications/Cuprum.appSubsequent updates apply automatically (they go through the in-app updater, not the browser, so they don't re-trigger the warning).
crates/ Rust workspace (core, cli, project model)
cuprum-ui/ Tauri 2 + React desktop app
testdata/ Sample Gerber files
docs/ Vision, design system, and development notes
See docs/DEVELOPMENT.md for contributor notes (notably:
bump the relevant disk-cache version tag when you change derived output).
- Gerber parsing builds on
MakerPnP/gerber-viewer
(MIT OR Apache-2.0), forked and trimmed to the parsing core under
crates/cuprum-gerber/src/viewer.
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.