MendelMax 1.5 Optical Y-Endstop Mount
This clip snaps on to 20mm aluminum extrusion and allows you to mount an optical endstop sensor (19mm spacing on optical sensor holes).
EDIT: Added "Micro Clip" which is based on the same source file. The clip can be used to hide cables in the groves of the extruded aluminum.
I will not grant Thingiverse an unconditional license to my source files so please go here for the Solidworks part files
https://github.com/KaiserSoft/3D-Printing