Dec 2017 All updated to a version I have saved as "V22".
Step and Iges files available at Grabcad (https://grabcad.com/library/dag-geared-belt-extruder-1)
BOM:
3mm Pneumatic fitting, M5 (for outlet)
3mm id 7mm od  3mm thick ball races (four needed, fitted inside the 13 T gear/belt pulley)
(this is almost certainly overkill, and 2 would do, but they are cheap and fitting 4 is easier than trying to hold two in the correct places)
608zz ballraces (8mm id, 22mm od, 7mm thick)  "skateboard ballrace", three required.
8mm *60mm bolt and nuts for main drive (you may also need washers to help this fit "nicely")
M3 bolts : 8mm (three for holding the motor)
20mm two for the casette
30mm, three needed, two for the outlet, one to hold the casette in the main bodies.
35 to 40mm for the tensioning screw (you may be able to use a 30mm)
M3 brass press in inserts (4mm dia) five needed
M3 grub screws or short 8mm bolts and nuts for the Herringbone gear version.
One M3 nut for the tensioning screw (or use a brass insert)
M5 30mm…