This is for quickly changing the effective endstop positions on the Ultimaker. (Note: I'am not very happy with this approach and probably will abandon it in favour for another.)Not yet working, needs tweaking. Stick the big part onto the front top-rim of your ultimaker (another on the left) Clamp it with the small parts & M3 screws from behind. The idea is that one slider can be opened slid along the longhole and closed on the fly. Its intended as a means for a quick toolheadexchange on the Ultimaker Generic HeadMount http://www.thingiverse.com/derivative:28248