I came across an article that describes a new process to add full spectrum color to 3D printers that use filament. The article can be found at http://www.3ders.org/articles/20140216-3d-color-printer-wins-innovation-competition.html. In a nutshell, two young chemical engineers won prizes at the Innovation Days competition at UW-Madison for a process that allows for an automated, continuous and variable coloring process for 3D printing. This add-on to existing FDM 3D printers applies solvent dyes directly to clear plastic filament which allows for differential color modulation within a single layer (very much like an inkjet printer). Since, in my biased opinion, Zortrax is on the cutting edge of quality home 3D printing, I thought they might like to look into this as a future add-on to the M200.
Yes would be nice 
I read that article few weeks ago, but surprisingly it doesn’t mention anything how it’s done.
And no any pictures even googling for it I saw only machine but is result which it produce is acceptable or just very poor coloring then is big unknown without pictures of colored prints.
Best Regards
Few weeks ago i wondering if something like this is possible. But there must be some big printhead…
My thought about this was something like remix of normal printhead and modified filament maker. In modified filament maker there must be some chamber where is mixed clear filament with color pigment.
The software would have to calculate the time to change the color and make extra wall/support on the side of the print area to “clean” the printhead of the unwanted, previously used color.
In theory it’s simple, but in practice there will be problems with make solid and vivid color as we want 
and this be only efficiency in changing one color per layer… not in precise printing multiple color per one layer
The way I would like to see Zortrax handle color would be in two parts. First you would access the Zortrax software suite and download an STL object. Then in the software suite there would be a new button for paint. You would use the tools provided to paint the object, and then you would slice it as usual. On the hardware side, on the printer, you would attach a small inkjet-like nozzle to the printhead. After the printer prints each slice of the object, the inkjet nozzle would deposit dye along the outer edge of the object (no need to color the interior). After the color has been applied, the printhead would start printing the next slice of the object. The inkjet nozzle doesn’t have to be particularly large or heavy because you’re only coloring the outside of the object. When you are finished, you will have a full color object.
Of course, I’m no expert (not even close). I’m sure Zortrax would be able to figure out the best way to add full color to a print.
To my knowledge the first post talks about coloring filament before it prints not the actual object.
Also dyes need to be solvent like in solvent printers. The only problem is how they put dyes on round filament and how they dry it before it enters the printer head for extrusion.