About this 3D model
I couldn't find any suitable opto endstop holders for my MendelMax, so I created my own. Those are intended for the MendelMax 1.0 kit available from RepRap-Fab, using Jonas Kuehling's X ends http://www.thingiverse.com/thing:18384 upper mounted Z motors, and opto endstops from RepRapSource. In case you want to modify the design to also fit as max endstops, I also include the scad source files.