Drivers and circuit board.

[Black Rabbit]

Sorry i'm not gonna be a big help for you, using several different motors together might be difficult if not impossible. You need a certain minimum torque to move your axis and a minimum steps per cycle to meet precision versus speed- demands. It might work though with some luck and a lot of work. But might i suggest buying some stock motors like reptrap compatible ones, prices of these are not exorbitantly high... As for electonics: you could also consider an arduino board with a ramps on it, you can buy them for about 80 euro's including pololu's (chinese pca's but they work ok), or do the right thing and buy the real stuff for some more. Good luck on your build, let us know how you fare!

p.s. i use 3 mm filament, no melting problems so far, but i guess the extrudermotor needs some more torque in comparison to 1.75 mm.