The Phantom Edit - MK8 Direct Drive Bowden Extruder for 1.75mm Filament

This is a remix of phantomoperator's direct drive bowden extruder. Thanks to phantomoperator for including the STEP files with his design, so that I could easily modify the designs. The original design can be found here... http://www.thingiverse.com/thing:946461

Differences from the original design:
- Uses a 625ZZ bearing and M5 bolt in place of the 608ZZ bearing and 8mm rod.
- Added a piece of 3/16" OD, 0.035" wall tubing to the idler to act as an anti-crush tube and bearing surface for a