There is this great hotend called a diamond hotend, which can be used to print in 3 colors and mix them into hundreds? of colors. This can for example be used with Red, Green and Blue filament to mix a RGB palette. They don't have to be these colors, but I believe RGB would give the maximum range of colors when constrained to 3.

However true RGB in physical printing would use separate colored voxels to create the appearance of a color, just like monitors display colors. As far as I know only HP Jet Fusion 3D printer uses this process, but it uses a process vastly different from normal diy 3D FDM printers.

CMYK is mixed physically like you would mix watercolors together to make new colors. It is used for printing on paper by all laserjet and inkjet printers (and in printing presses). So that means even the 3 input diamond hotend is actually mixed like CMYK. Repetier firmware v92.9 has this built in with support up to 16 inputs for a nozzle, but Marlin firmware v1.0.x only supports 4 inputs per nozzle at this time.

Using RGB for the 3 inputs of a hotend, means the printing color palette lacks White and also it seems that CMYK would give a bigger range of colors. That brings our tally to 4 inputs. It still needs a white filament to print white, so that means 5 inputs. And while we are at it, probably a 6th input would be useful: like for printing black infill (to save using CMYK to mix into black) or for using transparent filament or elastic filament.

So why isn't there a nozzle with 5-6 inputs already? Could it be done? Are there such hotends already?

P.S These are just theoretical assumptions. I just discovered 3D printing and I am in the planning phase of building my first 3D printer, so I am a total n00b in this. Please correct any assumptions I got wrong.

  • $\begingroup$ Possible duplicate of What is stopping us from mixing 3d filament colors in an Extruder? $\endgroup$ – Tom van der Zanden Oct 17 '16 at 7:06
  • $\begingroup$ This is a specualtive "what-if" question. This site isn't really for brainstorming on possible new developments. Also note that some 3D printing techniques do offer full CMYK (the former ZCorp, 3D systems, Objet, MCOR,...) but they don't use FDM. $\endgroup$ – Tom van der Zanden Oct 17 '16 at 7:08
  • $\begingroup$ my goal is to find out if this type of nozzle already exists and I just suck at googling $\endgroup$ – allanlaal Oct 17 '16 at 7:29
  • $\begingroup$ Do not forget WHITE, adding black alone will not move any of the three individual color to lighter shades. I posted my view on this in the similar discussion that Tom van der Zanden mentions. If you want 5 or 6 nozzles then look at Palette. But it does not do mixing just multicolor switching on the fly. $\endgroup$ – spicetraders Oct 17 '16 at 16:42
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    $\begingroup$ @TomvanderZanden it's technically not a duplicate as OP is asking about a different color delivery system. The link you posted was specifically with regard to using markers/pens to "paint" the filament. This question takes it a step further by asking if there is currently a system that beats the marker/pen setups with use of the actual color ingredients. $\endgroup$ – tbm0115 Oct 19 '16 at 14:58

You can find a full color hot end with CMYK+White if you look here https://www.reprap.me/diamond-fullcolor-hotend.html

  • $\begingroup$ although a short answer and probably breaking community guidelines, this is exactly the part I was looking/waiting for $\endgroup$ – allanlaal Feb 8 '18 at 16:14

You may be a bit misled here. First of all, you do not want "RGB" , as those are additive colors such as used when combining light sources. You do want "RYB" (red-yellow-blue) or the more accurate CMY(plus K just to get a 'truer' black) for subtractive colors.

Next, there's really no reason to attempt pixel-mixing. What should happen, ideally, is that pigments get fully mixed upon extrusion so that the desired color is actually in place. Pretty much any pixel-based setup will not "blend" into the desired visual perception. And as you propose, you really need a White and a Black to adjust the saturation (take a look at the Wikipedia pages on Hue and Saturation color maps).
So I'm not convinced that separate extrusion heads will ever get you a decent color continuum. I don't know if anyone has, or is planning, a multi-input, single-output head but I'd sure like one.

  • $\begingroup$ There's the Diamond head which combines 3 inputs and mixes them somewhat into 1, it costs around $30 on ebay. I've also seen plans for a 6-in-1, but no actual product. Thank you for the note about RYB :) $\endgroup$ – allanlaal Oct 18 '16 at 22:23

So whilst this is not quite what you were talking about I think this is the closest to the effect you’re looking for that I’ve seen.


This da Vinci printer uses a CMYK inkjet to colour a white filament as its being extruded. This allows for very quick changes in colour as well a nearly infinite combination of colours.

This means it only needs a single extruder and hotend but obviously the hotend needs to be built to allow the injection of pigment from the inkjet.

  • $\begingroup$ The problem with your answer is not that it "is not quite what you were talking about", but rather that is not... an answer to the question being asked. :) Yours would be better suited as a comment to the question instead, as it is still likely to be of interest for the OP. :) $\endgroup$ – mac Feb 4 '18 at 22:18
  • $\begingroup$ this is indeed interesting. DaVinci saw the same gap in the market as me 👍 $\endgroup$ – allanlaal Feb 7 '18 at 0:28
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    $\begingroup$ @mac point taken😜 I guess I made it an answer because OP didn’t say whether he was looking for a part he could use or just a solution to the problem. If it’s the latter than I think this is in fact an answer but I can see how it might be more appropriate as a comment. $\endgroup$ – Nick Dancer Feb 7 '18 at 7:45

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