I think the process is prohibitively complicated for filament FDM printers. From what I understand, mixing fluids that are in laminar flow would require a large working area which you don’t have in a 3d printer. On the fly, from the printer, is SO MUCH more than what a 3d printer is already doing. It would basically be a color mixing chamber, at melting temperature, and then extruding back into a new filament at the correct diameter to run through the rest of the printer - may as well do that separately from the print process.
However, I think this would work so much better without starting at filament and using pellets instead. There are pellet hopper FDM 3d printers out there, though not nearly as common as filament printers. But you could have a system of 4 hoppers of pellets that let out measured ratios into a primary hopper that agitates and mixes the pellets (while still solid) and then feeds them through print head like normal. Although, the normal size of pellets might be a bit big to get a good mix that isn’t just a splotchy mess, once the hoppers and mixing is figured out you should be able to find a path to smaller pellets.
That said, I do also like the idea someone else had of using a neutral color filament and then having a process of adding pigment somewhere along the way to the nozzle.
Crozekiel@lemmy.zip 1 week ago
Welp, I gotta eat my words on this one. Not only is it definitely doable, apparently it’s already a thing. I stumbled across this by coincidence just now.
https://reprap.org/wiki/Diamond_Hotend