This is an adjustable Z Endstop for the RepRap G3D (Prusa i3 design from Gadgets3D) printer. I found that the original endstop mount was difficult to fine-tune due to the screws binding and twisting with the mount. This design uses a spring loaded pivot arm instead. The position is adjusted with a screw. There is a bracket that mounts to the original frame slot with two bolts. The top bolt is leveraged as the shaft for the pivot arm. A small spring is used between the two pieces to retain tension on the arm against the adjustment screw.
I had to relocate the endstop for the X-Axis so I have included a bracket for mounting the switch to the rod. 2016-01-23 Update: Cleaned up Sketchup file.