Multiple & parametric filament extruder

Along with palette(http://www.thingiverse.com/thing:118529) i made a parametric extruder based on these (http://www.thingiverse.com/thing:10783, http://www.thingiverse.com/thing:16429). It's far from finished but it can work :) i started with a simple motor base, but it can be changed with a typical Wade's or others, as the only thing it needs are 2 holes.
I'm trying to use the whole system with 2 motor drivers in order to be compatible with RAMPS 1.4.

https://www.youtube.com/watch?v