This is a 2-piece groove mount holder I made for my E3Dv5 clone on the Rostock's original platform. It can be assembled with M3 screws, and then attached to the Rostock effector with M4 screws (not sure why, but it looks like that's the hole size in platform.scad). I intend to figure out a way to retrofit the Kossel's retractable probe onto the top of the platform using the limited amount of screwholes the Rostock's effector has.