I've added proximity swiches to my workbee The proximity switches work with the blackbox when you move the internal jumper from 5v to 24v the parts were sourced here in Canada from Sienci Labs. I had to lengthen the cables for the Z and X. The 3d printed bracket that holds the z switch came with the Sienci Labs proximity sensor kit for the Longmill mk1. I simply drilled a hole in the correct location for a screw. The angle bracket on the x carriage is held in place by the same screw that bolts the z carriage to the x carriage I put a tee nut on the angle bracket attached to the zee to incease the odds that the switch will pick it up. probably not necessary.
