Here's my take on an end-stop for 1515 beam on Mini Kossel printers. I wanted something that encapsulated the micro-switch, but also that put the mounting screw on the outside of the beam. The SS5 micro-switch slides into the hole, and you can put a couple of screws through the holes to secure it. The inner bumps don't go very deep so you can have wiring inside your 1515 channels passing through this end-stop. Of course it can be mounted either way (up or down), as per the original.