I have been building Kromacut, a browser-first app that turns a 2D image into a stacked, color-layered 3D print. Kromacut is an open-source HueForge alternative for turning images into layered filament 3D prints.
The mental model is simple: image colors become physical layers. Kromacut reduces an image into a printable palette, lets you tune how those colors stack, previews the result in 3D, and exports files you can take into a slicer.
It started as a free, open-source HueForge-style experiment. Since then it has grown quite a bit. My older write-up listed things like 3MF export and automatic color blending as future ideas. Those are no longer future ideas; they are in the app now.
The basic workflow
You load an image, clean it up, reduce the colors, then switch into 3D mode.
From there, Kromacut has two main workflows:
- Manual mode gives you direct control over color order, per-color layer heights, pixel size, layer height, and filament swap instructions.
- Auto-paint mode starts from your real filaments instead. You enter filament colors and Transmission Distance values, and Kromacut plans the physical stack for you.
This is how the first mode looks like, it's a screenshot from an older version of the app:
The second mode is the more interesting recent addition. Transmission Distance, or TD, is a way to describe how translucent a filament is. Thin layers of semi-transparent filament can blend visually, so stacking white over red might produce a pink-ish result instead of just a hard color change.
Kromacut uses a Beer-Lambert-style optical simulation to estimate those blends. It can also calibrate TD values from test samples, optimize filament order, and prioritize the center or edges of an image when matching colors.
That is what the screenshot above is showing: 3D mode with Auto-paint active, a saved filament profile loaded, TD values beside each filament, and the layer preview bar along the bottom showing the physical color swaps across the finished stack.
The part that got surprisingly serious
The fun part is the UI: upload an image, drag some controls, watch the model update.
The less glamorous part is making sure the exported model is actually printable.
A model can look fine in a WebGL preview and still produce slicer problems: non-manifold edges, inverted winding, duplicate triangles, missing layer objects, or weird material assignments. A lot of Kromacut's recent work has been around that boring-but-important boundary between "it renders" and "it slices."
Current exports include binary STL and 3MF. The 3MF path preserves physical filament colors where possible, especially in Auto-paint, so the slicer sees the real material colors instead of a bunch of preview-only blended colors.
There is also optional smooth meshing, progress feedback for long builds, desktop builds through Tauri, and in-app documentation for the full image-to-print workflow.
Stack
Kromacut is built with:
- React, TypeScript, and Vite for the app
- Three.js for the 3D preview
- Tauri for native desktop builds
-
node:testand Playwright for regression coverage
The geometry tests are especially important. They check things like manifold edges, winding, layer counts, and 3MF material consistency because 3D printing bugs often hide in places screenshots cannot catch.
Releases, desktop builds, and contributors
The web app is still the easiest way to try Kromacut, but I also publish native desktop builds through GitHub Releases.
The latest public release at the time of writing is Kromacut v3.0.0, published on June 1, 2026. That release includes Windows installers, including an offline installer with WebView2 bundled, macOS DMGs for Apple Silicon and Intel, and Linux packages such as AppImage, .deb, and .rpm.
The desktop app is built with Tauri, so it keeps the same browser-first UI while giving users a native app wrapper with a few desktop specific features like checking for updates, and more recent work is also adding desktop settings for checking updates manually and controlling whether update notices run at startup.
Kromacut is mostly a personal open-source project, but it is not meant to be a closed solo island. Troughtout development the app received not only feedback and ideas, but also code contributions from other people. Issues, test cases, filament profiles, print results, and weird slicer reports are all genuinely useful contributions too.
Try it
You can try Kromacut in the browser here:
The source code and releases are on GitHub:
https://github.com/vycdev/Kromacut
It is open source under AGPL-3.0-only. As of June 2026, the repo has crossed 200 GitHub stars, which is honestly very cool for such a niche 3D printing tool.
If you are into filament painting, lithophane-style prints, or weird little tools that turn images into physical objects, I would love feedback. Especially from people who actually print things with it, because slicers have a talent for finding problems that software previews politely ignore.
How the app evolved
If you want to see the project over time, these older posts give a pretty good timeline:
- September 23, 2025: Original Reddit launch post - the first public version and the early feedback that shaped a lot of the next work.
- October 23, 2025: Patreon visual upgrade post - a look at the UI overhaul, new logo, and early usability fixes.
- November 15, 2025: YouTube walkthrough - a video explaining what HueForge-style printing is, why I made Kromacut, and how the app worked at that point.
- November 15, 2025: Reddit follow-up post - the community update around the video and visual refresh.
- December 21, 2025: vycdev.com project write-up - a longer blog-style recap of the launch, reception, and the features that were still planned at the time.
- March 14, 2026: Show HN post - the Hacker News version of the project pitch, after Auto-paint, desktop builds, STL/3MF export, and the browser-first workflow had become the main story.
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