Before going for quad extrusion it may be worth to experiment with dual extrusion. Especially if your controller already supports dual extruders without any additional hardware. Here's how I did this
Extruders: https://www.thingiverse.com/thing:2016289
2 into 1 https://www.thingiverse.com/thing:2088835
test object https://www.thingiverse.com/thing:2484662
Facebook Hypercube group https://www.facebook.com/groups/1871049783171141/
