http://prusaprinters.org/original-prusa-i3-mk2-multi-material-upgrade-release/ Not sure I would do this now with the duel x carriage on the horizon but I really like the idea.
I saw that too. Like how you can change up to four reels. I'm sure there will be complications though, and I'm not sure if it could cope with different types of filament (i.e. conductive or dissolvable)..?
It probably can but you would have to wait for the nozzel to get to the proper temps every time you change colors or materuals. Would make for a long print time. The other thing I would be worried about is running molten filament up into the Bowden tubes. I am sure they are doing a quick purge and retract but if any soft stuff remains could easily catch and jam I would think. Lastly it's Bowden so you have to deal with that, would be cool if somehow you could have that set up feeding a direct drive head but the engineering on that would be daunting indeed.