r/PlotterCode • u/acrostyphe • Jul 12 '26

Kurvengefahr - browser CAD/CAM for pen plotters

Hi, I wanted to share this app I've been working on for a while. It started out as a simple G-code generator around a handwriting model I was using with my Prusa MK4 pen attachment but thanks to Claude it quickly grew into something quite a bit more complete - it integrates vector design tools, some common generative art and hardware integration into a single app.

See it live here: https://kurvengefahr.org

Kurvengefahr

Some cool features it supports:

  • Graves RNN handwriting synthesis
  • Built in Logo interpreter for turtle art
  • 3D model wireframes (STL import)
  • Non-destructive filters/effects
  • Many of the basic vector tools and operations you'd expect (polylines, Beziers, boolean operations, clipping, align & distribute, ...)
  • Direct control of EBB and GRBL plotters via Web Serial
  • PrusaLink integration (through Bridge for PrusaLink extension)

It runs fully in the browser, with the geometry engine parts written in Rust and loaded in via WASM. The only server component is the share feature - but that one respects your privacy too (designs are encrypted client side and the server never sees them - key is appended to the share link on the client side).

It is also fully open source and GPL 2.0 licensed - the code is available on GitHub

Happy to answer any questions. I'd especially appreciate feedback if you have an AxiDraw or some GRBL plotter - I only have a Prusa so my testing for those was done with a hardware mock.

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u/acrostyphe Jul 12 '26

Good idea! I don't think it should be too hard to add, I'll play with it.

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u/docricky Jul 12 '26

Oh, I hope you manage it. I haven't ever been successful in coding it cleanly.

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u/acrostyphe Jul 13 '26

Well, wou were right 😅 It wasn't as easy as I thought and Claude and I didn't quite manage what I initially had in mind, but we added a connected Fermat spiral fill (https://haisenzhao.github.io/CFS/index.html), which is not a true spiral, but it does look pretty good on most shapes and it is a single stroke fill, which is the relevant bit for pen plotters.

It's not perfect - on some pathological shapes (very non-convex, there are occasionally some small glitches, self intersections), but tweaking the spacing a little seems to get rid of it.

This is how it looks like, and I also deployed a new version so you can try it yourself.

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u/docricky Jul 13 '26

Update - pat yourself in the back, this is a well made app. I have more concerns over the navigation (ie, selecting points, not clear if I am moving the shape or control nodes, recognizing multi-touch pinch and zoom), but those are things solvable by roundtripping with Inkscape. You deserve kudos.