I remember the utter dismay I felt when I was looking to buy my first 3D printer. They all seemed to print in just one color. Plastic things were all around us, and they didn’t seem to be limited to just one color — so why couldn’t 3D printers print in lots of colors, too? It wasn’t until I started printing that I began to understand the technical challenges of getting more than one color into a model that was built one G-code line at a time.
For this article, we’ll focus on filament-based 3D printing, also known as FDM (fused deposition modeling) or FFF (fused filament fabrication), specifically in the consumer and hobbyist realm. Color printing does exist at the industry level with a variety of other technologies, but none are at a price point that can be easily scaled down to the consumer level.
What have become accessible and prevalent are the familiar printers that can accurately re-create a 3D model by melting filament of various polymers. So our multicolor problem is, how do you stop printing in one color filament and start printing in a second color? What about a third, fourth, or even 10th color?
Solving this problem has been a challenge that has been approached from multiple directions. In rough historical order, they are:
Independent dual extruder (IDEX): The first multicolor hobby-level printers were developed with two separate extruders, each able to print a different filament, enabling two-color models. These machines can print in multiple ways, with some providing the ability to print the same model twice at the same time. IDEX printers are still popular today and are available from multiple manufacturers, for example the Sovol SV04 printer.
Color blending extruder: Other companies, like Geeetech, took a different approach to multicolor printing by bringing two or three filaments into the same hotend. This color mixing configuration, along with customizations in the slicer, gives the printer the capability not only to print in multiple colors but also to blend the colors together. It can print the model with a gradient across colors, or use a percentage blending between the two, or print specific colors in certain locations.
This style of printing has remained more niche, partly due to challenges with nozzle clogs and hardware reliability, and partly because the software isn’t mainstream and can be challenging to decipher (I was never able to get it functioning beyond basic gradients). However, many have enjoyed printing multicolor prints this way. Geeetech still sells their two- and three-color printers as well as a new Mizar M model that combines both approaches: dual extruders and color blending within one nozzle.
And for those wanting to modify their existing 3D printers, replacement blended nozzle hotends have recently become popular, with multiple brands selling hotends with two, three, and four filament inputs.
Filament swapping: To have true multicolor printing, a combination of new hardware and software was needed. In 2017 Prusa Research debuted their Multi-Material Upgrade (MMU), an additional filament swapping module for their Prusa MK2 i3 printer that made printing in up to five different colors a possibility. This was coupled with model painting and slicing functionality in PrusaSlicer software to create a G-code file that could tell the printer to print in one color, retract that color, move to the next color, print, retract, etc. until the model was complete.
Printing in this manner requires an additional step that adds significant waste to the printing process: purging filament. Because only one extruder is being used, when one filament is retracted and the next filament loaded, there is still melted plastic in the hotend from the prior color. In order to get to a “clean” color, the prior color needs to be pushed out. This is done via a purge tower or wipe tower: the extruder lays down lines of filament until it’s estimated the old color has been purged out.
Purges need to be done once per color change per layer of the print, and are deposited over on the side of the build sheet. In the case of four or five colors, the filament used to purge until the next color is extruding cleanly can easily be larger in weight/volume than the model being printed!
Filament splicing: Other technologies were also in the works. Mosaic Manufacturing’s Palette was a solution that could be used with any 3D printer, unlike the MMU which was specific to Prusa’s. The Palette 2 supported up to four colors of filament, and Mosaic’s Canvas web-based tool was used to paint the model and define printing parameters. From there, a customized version of the model was sent to the printer, and the Palette was told to begin preparing filament for the printer.
The Palette managed multicolor printing in an entirely different way: by splicing together the filament into sections as long as the printer would need to print that color on each layer. The Palette worked with any printer because the printer had no idea it was printing in multiple colors. It was receiving a single strand of filament, spliced together by the Palette and fed to it as it printed the model. The concept was elegant, the execution was complex, and the engineers at Mosaic made it all work together.
There was still the purging problem, though. Even though the filament was spliced together for the proper lengths the model would need, those lengths had to be extended so the color change could make it to a pure color (no one wants red bleed into white filament, for example). Which left us with purge towers and a lot of waste. That was just the price we had to pay for changing colors with just one nozzle.
Hold that thought, because there are ways we can reduce that cost.
Many Multicolor Modifications
Palette 2, which had some reliability issues, was replaced in 2021 by the more robust Palette 3 (above), which could print in up to eight colors with more reliability. In 2023 Prusa Research released their updated MMU3 for Prusa printers, also with more reliability.
It is here that you might think you’re hearing about a lot of “reliability improvements.” As it turns out, printing in multiple colors is hard. Loading one color, unloading it, loading the next color, unloading it, and then repeating that a thousand times is a lot of manipulations with filament. Whether you’re just loading or splicing, there are a lot of parts in play to make those pretty multicolor prints.
More filament swappers soon followed. 3D Chameleon has a color changer that adds four-color printing to any 3D printer. A recent Kickstarter, Co Print, promises fast color 3D printing with up to 20 colors that works on any 3D printer. And there’s the Enraged Rabbit Carrot Feeder (ERCF) for Voron printers.
All of these are modifications that are added to printers. But none was designed as a true multiple color 3D printer. That is, until Bambu Lab came on the scene via Kickstarter and took the world of multicolor printing by storm with their printers that poop.
Bambu Lab Gets There First
Bambu Lab came out of nowhere in 2022 with their X1 Carbon printer and its AMS (Automatic Material System) that had four-color printing with a filament swapping hub that increased the number of colors up to 16.
The way the filament is managed by these new printers involves a lot of loading filament in through a long series of Bowden tubes, printing that color, unloading it, loading the next color and then, instead of printing a purge tower, the printer makes a little squiggle of filament that it then ejects out the back of the printer. It is unlikely Bambu Lab intended the term to be poop, but once it was said, the term stuck.
And here’s the thing. The reliability and print quality coming from these printers, started by a team of ex-DJI executives, was unparalleled. They successfully fulfilled their Kickstarter pledges, and sales continued to go up based on print results and user endorsements. Many of the sales were from existing customers buying a second or third printer. Since then, Bambu Lab has released additional printers such as the new A1 and A1 Mini, all with multicolor printing capability.
Did this solve the multicolor waste problem? Nope. It only changed the way the waste was created, from purge blocks to piles of poop. Just as in the other technologies, tuning and other options can reduce the waste or redirect it to other areas, but the waste is still there.
A Tool Change Will Do You Good
Does this mean we’re stuck with lots of waste for multicolor printing? Not necessarily. In all the technologies above that give us more than two colors, we’ve had just a single extruder. But there are also tool changer 3D printers which have separate extruders for each color or material. E3D sold one in 2018, a proof of technology that is no longer in production, but the new Prusa XL from Prusa Research has up to five toolheads that can do multicolor printing with very little waste.
Because each extruder maintains a single color, there’s no need to purge between color changes; only a tiny priming bit of filament is extruded to ensure the filament is flowing normally. Models printed in five colors create only a few grams of filament waste in their little priming tower, vastly less than single-extruder machines.
There is a different price to pay in this case though, and that’s cost — about $3,500. Five extruders are more expensive than one. However, that cost may become competitive with single-extruder solutions in the future, with other color-changing machines bringing down prices. One new tool changer currently on Kickstarter is the Proforge 4 from Makertech 3D, which has four toolheads for about $2,000.
And that brings us to our last and latest multicolor printing product that has only just been shown at Formnext 2023 in November: AnkerMake’s V6 Color Engine. This innovative-looking upgrade for their M5 printers has six little extruder/hotends built into one big print head, where each hotend rotates into place for fast color changes without the need for purging the prior color. Is this the next advancement in fast, low-waste multicolor printing we’ve all been waiting for? We hope to test it soon and find out!
This article first appeared in Make: Volume 88.
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