There is such thing as "color-.stl" fileformat, where color information is included.
Now we need a board that can handle 3 or more extruders. ( 5 would be nice for cyan, magenta, yellow, black, white )
The only board I know is the
duel board with arduino due processor.
But the guys who developed the diamond-nozzle, may have their own design in the pipeline?
Time will tell, if there is demand for FDM full color printers.
-Olaf