Recently frustrated by the limited X/Y travel on my Prusa Air 2 >(https://grabcad.com/library/3d-printer-prusa-air-2-1) i wanted compact end stops. Using cheap readily available micro switches, i designed this housing with 2 types of arms > 1 standard + 1 for Z stop adjustment.
Needs 1 M3 allen head X 30mm bolt, 2 plain washers & a Nyloc nut.
Same again plus spring if you want fine adjustment on the Z endstop arm version

8 mm smaller profile than the standard ones ...works for me!

Update Oct 7th 2015 > Added a housing that fits onto a 10mm dia rod ( as apposed to the original 8mm )

May add LED indicators later !