This is a compact Bowden extruder for MK8 drive gear and 1.75mm filament. Its constrained filament path allows it to print well with all filaments, including flexibles.
Update 5/13/16 - The file has been modified to accommodate drive gears whose set screws protrude more out from the body of the drive gear.
3 M3 x 20mm Machine Screw
1 M3 x 14mm Machine Screw
2 M3 Hex Nuts
1 3mm x 10mmm x 4mm Bearing (623zz)
2 M3 x 40mm Machine Screw if you use springs on the extruder arm
2 M3 x 25mm Machine Screw if you do not use springs on the extruder arm
1 M6 Hex Nut
1 Bowden Push Fitting with M6 Thread