color mixing

4 Articles

Two test towers, showing the palette potential of three (R, B, Y) filaments.

FullSpectrum Is Like HueForge For 3D Models, But Bring Your Toolchanger

March 17, 2026 by 20 Comments

Full-color 3D printing is something of a holy grail, if nothing else, just because of how much it impresses the normies. We’ve seen a lot of multi-material units in the past few years, and with Snapmaker’s U1 and the Prusa XL, it looks like tool changers are coming back into vogue. Just in time, [Ratdoux] has a fork of OrcaSlicer called FullSpectrum that brings HueForge-like color mixing to tool-changing printers.

The hook behind FullSpectrum is very simple: stacking thin layers of colors, preferably with semi-translucent filament, allows for a surprising degree of mixing. The towers in the image above have only three colors: red, blue, and yellow. It’s not literally full-spectrum, but you can generate surprisingly large palettes this way. You aren’t limited to single-layer mixes, either: A-A-B repeats, and even arbitrary patterns of four colors are possible, assuming you have a four-head tool-changing printer like the Snapmaker U1 this is being developed for.

FullSpectrum is, in fact, a fork of Snapmaker’s fork of OrcaSlicer, which is itself forked from Bambu Slicer, which forked off of PrusaSlicer, which originated as a fork of Slic3r. Some complain about the open-source chaos of endless forking, but you can see in that chain how much innovation it gets us — including this technique of color mixing by alternating layers.

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A graph is shown of the percentage reflection of visible light as a function of wavelength. Four lines are traced on the graph, which all approximate the same shape. In the top left, two purple shapes are shown, which the spectral chart describes.

Paint Mixing Theory For Custom Filament Colors

April 28, 2025 by 11 Comments

Recycling 3D filament is a great idea in theory, and we come across homemade filament extruders with some regularity, but they do have some major downsides when it comes to colored filaments. If you try to recycle printer waste of too many different colors, you’ll probably be left with a nondescript gray or brown filament. Researchers at Western University, however, have taken advantage of this pigment mixing to create colors not found in any commercial filament (open access paper).

They started by preparing samples of 3D printed waste in eight different colors and characterizing their spectral reflectance properties with a visible-light spectrometer. They fed this information into their SpecOptiBlend program (open source, available here), which optimizes the match between a blend of filaments and a target color. The program relies on the Kubelka-Munk theory for subtractive color mixing, which is usually used to calculate the effect of mixing paints, and minimizes the difference which the human eye perceives between two colors. Once the software calculated the optimal blend, the researchers mixed the correct blend of waste plastics and extruded it as a filament which generally had a remarkably close resemblance to the target color.

In its current form, this process probably won’t be coming to consumer 3D printers anytime soon. To mix differently-colored filaments correctly, the software needs accurate measurements of their optical properties first, which requires a spectrometer. To get around this, the researchers recommend that filament manufacturers freely publish the properties of their filaments, allowing consumers to mix their filaments into any color they desire.

This reminds us of another technique that treats filaments like paint to achieve remarkable color effects. We’ve also seen a number of filament extruders before, if you’d like to try replicating this.

Digital Paint Mixing Has Been Greatly Improved With 1930s Math

January 30, 2025 by 41 Comments

You might not have noticed if you’re not a digital artist, but most painting and image apps still get color mixing wrong. As we all learned in kindergarten, blue paint and yellow paint makes green paint. Try doing that in Photoshop, and you’ll get something altogether different—a vague, uninspiring brownish-grey. It’s the same story in just about every graphics package out there.

As it turns out, there’s a good reason the big art apps haven’t tackled this—because it’s really hard! However, a team of researchers at Czech Technical University has finally cracked this long-standing problem. The result of their hard work is Mixbox, a digital model for pigment-based color mixing. Once again, creative application of mathematics has netted aesthetically beautiful results!

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Build Some Entertainment For Young Holiday Guests

December 26, 2015 by 1 Comment

Need a good excuse to duck out on the family over the holidays and spend a few hours in your shop? [Jens] has just the thing. He built a color-mixing toy that looks great and we’d bet you have everything on-hand necessary to build your own version.

The body of the toy is an old router case. Who doesn’t have a couple might-be-broken-but-I-kept-it-anyway routers sitting around? Spray painted red, it looks fantastic! The plastic shell hosts 6 RGB LEDs, 3 toggle switches, and 2 buttons. [Jens] demonstrates the different features in the demo video below. They include a mode to teach counting in Binary, color mixing using the color knobs, and a few others.

Everything is driven by an Arduino Pro Mini. The lights are APA106 LEDs; a 4-pin through-hole package version of the WS2812 pixels. You could easily substitute these for the surface mount varieties if you just hot glue them to the underside of the holes in the panel. We’d love to see some alternate arrangements for LEDs and a couple more push buttons for DIY Simon Says.

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