true color printing with CMYK+White (not 3-in-1 diamond head RGB)
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.
Possible duplicate of What is stopping us from mixing 3d filament colors in an Extruder?
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.
my goal is to find out if this type of nozzle already exists and I just suck at googling
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.
@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.
You can find a full color hot end with CMYK+White if you look here https://www.reprap.me/diamond-fullcolor-hotend.html