This part is a mash-up of Jaydmdigital's Frame Top here: https://github.com/Jaydmdigital/Kossel_2020/blob/master/frame_top.stl and his End Stop Mount here: https://github.com/Jaydmdigital/Kossel_2020/blob/master/endstop.stl . When I built my 2020, I found mounting the end stops a real PITA so I think this should help. Each end stop is now almost assured to be equal(ish) distance from the bed and there is a hole to bring the wires from behind to attach to the end stop poles. I also removed some material from the frame top to allow running wires in the extrusion.