Touch probe for a CNC machine. This is a Renishaw type touch probe. Rather than spheres with soldered wires I use the tops of round head screws which are easier to position and connect together electrically.
This probe design uses standard parts from McMaster Carr, a couple of 3D printed parts and a simple inverting transistor circuit. The circuit is optional depending on your probe setup. The 3D printed parts could be replaced by another non-conductive material with the required features machined.
The CAD files (OpenSCAD, and STL format), schematic and parts list are located on the Thingiverse page for this tool:
CNC Touch Probe (Thingiverse)
(The mechanical and electrical parts lists are in the 'Instructions' tab on the Thingiverse page.)
Probe Mounted to CNC Mill:
Cover removed and disassembled: