Direct Drive Bowden Extruder for 20 mm extrusion

Direct Drive Bowden Extruder that latches on (bolt free) to 20mm extrusion. Can also be fixed in place with a single bolt. Features:
-simple, open, & compact
-easy to clean and adjust
-designed to be drilled out for 1.75 or 3mm filament
-designed to be drilled out for a 5mm or 1/8 coupling
-will work with the shown Arcol hobbed pulley or a mk7
-pulley is positioned close to motor base to reduce cantilevered load on motor shaft
Inspired by every other open source extruder out th