One Z-Motor / Filament holder solution for Prusa i3 Rework

This solution (expansion) is for the Prusa i3 Rework (http://www.thingiverse.com/thing:119616) and is an elegant way to build a Prusa i3 with only 4 stepper motors and a rock solid filament holder that uses the shorter m5 threaded rods (2x 300mm) from the BOM (http://reprap.org/wiki/Prusa_i3_Rework_Bill_of_materials) as poles for the filament holder, replaces the second z-motor with a bearing holder plate and only replaces the upper rod holde (z-axis top left/right) to produce as less garbage as