uStepper linear actuator

Derivative of: http://www.thingiverse.com/thing:45103

This is a compact derivative of the "Linear actuator concept for CNC machines" intended for stand-alone applications using a uStepper. Could be used as window or door opener for example. May be updated at a later point.

Hardware:
2 x 625ZZ bearings
2 x M3x35mm
4 x M3x8mm (or M3x10mm if using washers)
1 x M3x10mm (for the motor gear)
3 x M3 nuts
2 x M5 nuts
1 x M5 threaded rod
2 x M5 washers (if needed between bearings and ge