clough42 - I printed your belt drive extruder and got a nema 14 motor from pololu. It will probably be a week or two of resolving a few other issues I'm working on, but I will install it and see how the nema 14 does and if it works well. Using 3mm filament/j head/0.50 nozzle. The pololu part is #1207 Stepper Motor: Bipolar, 200 Steps/Rev, 35×26mm, 7.4V, 0.28 A/Phase = 12.95. I deliberately got a 26mm to see if the smaller size could possibly cut it.

Flywheeld: If it works well it could be a good one to use with this dual extruder. 26 mm x35 x35 case size.