This new device could be of interest to some people :D
https://www.kickstarter.com/projects/mosaic3d/the-palette-3d-printing-evolved?ref=tag
Maybe not too accurate on very small models, the filament change-over timing would have to be quite good.
this can only be used with printers that support gcode. Zortrax slices zcode so it will not be compatible.
Well this part could be solved, but I'm not so sure how this thing is supposed to stay synchronized. The only means they have are assumptions from the G-Code (which are not precise due to acceleration control etc. in the printer) and the "scroll wheel". So I would assume the slightest slip on this wheel will lead to major issue with the color mixing. Besides, I would think the exact distance from the device to the nozzle has to be known for this to work. Maybe/probably you can set it on the device but I would assume that needs quite a bit of calibration to work.