Multicolor RepRap prints the really, really hard way

[Adrian Bowyer] just posted his progress with multicolored printing to the RepRap blog.

The new developments are a continuation of [Adrian]‘s experiments with a mixer extruder that squirts four different colored filaments out of the same nozzle. [Myles Corbett] took this idea and ran with it producing the two-color print seen above. To squirt two different colored filaments out of the nozzle, [Myles] used two Bowden extruders mounted near the apex of the RepRap with tubes leading to the nozzle. Right now, the color of a print is controlled by loosening the grip screws of the extruder, but there are plans for moving that task over to electronic control of the extruders.

While it may be only black and white now, it’ll be a very interesting development once five extruders are loaded up with cyan, magenta, yellow, black, and white filament. Yes, it is now theoretically possible to print full-color 3D objects on a RepRap. While we’re not looking forward towards having to upgrade our one-motor extruder to a four- or five-motor model, the possibilities for desktop fabrication are becoming amazing.


  1. Kevin says:

    This is pretty awesome… much like inkjet… it’s plastijet printing…

  2. NickS says:

    Why not mix dye into the print head after the plastic is melted? The resolution probably wouldn’t be exact, but you could use plain white/clear plastic and get almost any color out without requiring multiple extruders.

  3. Guan Yang says:

    When you say “Yes, it is not theoretically possible to print full-color 3D objects on a RepRap.”, do you mean that it is NOW theoretically possible? If not, what makes it impossible?

  4. chango says:

    I wonder if the mixing (and cooling) can be done at the other end of the Bowden cable. You’d have to heat, then re-cool the plastic, only to have to heat it again, and have a motor for each feed mechanism plus the Bowden drive. But you’d get a lighter head and much more volume for a mixing manifold.

    • macegr says:

      ABS loses about 30% strength each time you melt it, so keeping the number of melt cycles to a minimum is best.

      For full-color heads, I think it would be ideal to have even thinner filament, 1.0mm or 0.75mm. The melt chamber would be smaller and there would be finer control over the color mix.

  5. Sean says:

    You need to 3d print a head in metal with a mixing path, like those new nozzles for 2 part epoxies. If it’s too thick to feed with the material itself, a powered mixing screw might work instead. You’d just need to start mixing the colors an appropriate amount of time ahead of where the print head is so by the time the mix comes out it’s right.

    • Dax says:

      Premixing has the problem that if you need only a small amount of a specific color, you end up wasting a batch of color that has to be purged out of the nozzle before the next mix can be pushed out.

  6. mjrippe says:

    Greyscale =/= multicolor. While this has potential, it is not fully realized yet. Avoid the hype.

  7. Steve-O-Rama says:

    Even if it is hyped, it’s amazing how far these printers have come in such a short amount of time. The drop in their costs have been remarkable, as well.

  8. Jason Stone says:

    Has anyone considered using translucent plastic and sending it through an inkjet printer head?

  9. PlastBox says:

    While 3D printing is cool and multicolor is a step in the right direction (towards awesomeness, that is), wouldn’t it be more prudent to focus on resolution? From what I’ve seen so far, neither the MakerBot nor the RepRap are capable of producing stuff with any acceptable level of finesse..

    Am I missing something here? In the articles main picture, you can clearly see the layers. Until 3D printers at the very least exceed the level of detail I can achieve with cheap cake decorating utensils, I ain’t buying one! =/

  10. rue_mohr says:

    “cyan, magenta, yellow, black, and white filament. ” AND CLEAR DONT FORGET CLEAR! people are gonna have great fun with printing sculptures with optic paths in them, then someone will discover the practical use for optic paths.

  11. Doug Keenan says:

    Fascinating! I’ve gone a different direction for color printing, using a four-to-one ABS filament switch, see prototype at website link.

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