This is mount plate for mechanical endstops to 2020 aluminum frame for Kossel. It has hollow for contacts, which bulged on back side of PCB. And guide pin for precise mount. Suitable for MGN-12 linear rails and maybe for other types of carriages.
Also, I've included SCAD-file, so you can adjust the thickness to match your carriages.
[UPD] Added v2 version, which requires less plastic, especially if you need thick mount.
[UPD2] Combined both versions in single file and adapted it for Customizer.