Simple Extruder Drive Block only 3 parts!!

UPDATE 7/27:Enlarged holes for push fittings on extruder body and holes on the arm for bowden tube if used. Enlarged volume above filament/push fittings for extra strength. Enlarged "footprint" around foot/cleat mounting holes on the body.
UPDATE: Created space for MK8 grub screw, added support for overhand on drive block. Added slightly more space for bearing clearance. Added indent on both sides of arm so only a 20mm M3 bolt is required. Created slight spacing for 608 bearing on arm.
While building my 150% Wilson TS Prusa i3, I've been rather unsatisfied with the available extruders. The closest I've come to what I prefer is Richrap's extruder on a custom mount I threw together in Sketchup. Unfortunately the effort required to change filament is more than I prefer.
This is a direct drive extruder for use with the MK8 hobbed pully.
My requirements are:

1. Simplicity - as few parts as possible. No monstrously long m3 bolts.
2. The ability to release filament with 1 hand.
3. The ability to mount this to 20mm 8020 extrusion
4. The ability to mount this in both left and right orientations.
   After a few days work I think I have it.
   BOM:
   1 x MK8 hobbed pulley
   3 x m3 x 6mm socket head bolts (block mount to stepper)
   1 x m3 x 20mm socket head bolt (through arm and block mount to stepper)
   3 x m3 washer (in between arm mount, under 20mm bolt on arm, in between spring and nut)
   3 x m3 nut (1 in tensioner, 2 nuts jammed together holding washer in place)
   1 x (really small) self tapping screw to go into axle
   1 x 608zz bearing - If you have a wades extruder around, you have one.
   1 x Spring
   STL's for both left and right facing extruders are included. The tensioner arm and the axle will work with both.
   Fitment is good - test extrusion working as intended.