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.1) Print the x,y,z endstop mounts.2) Re-drill, or clean the holes as needed.3) Mount the opto endstop PCB's to the plastics using M3x15 screws, washers and nuts. Use a washer between the PCB and the plastic so that you keep the same height as the soldered pins.4) Use M5x10 and M5 t-nuts to mount the Z and Y holders, Y min is at the rear right, Z min at the middle right. 5) The X min is mounted on the left X end replacing the M3 their with a slightly higher M3x30 screw. You might want to skip the middle PCB screw if it gets too tight. (You may also change the scad file and move the mounting hole more to the left, but you'll loose printing width then.)6) Mount your endstop flags (in my case I bended some copper sheet into the right positions) at the right X end for the Z stop. The X flag is mounted on the X carriage (I used an extruder hole to fix the flag with a screw). And finally the Y min flag sits on the back right screw of the printing bed.#7) Enjoy !