A Touchprobe for CNC in normally open mode made from an PT31 plasma cutter electrode and nozzle and a spring.

Can be mounted directly into the spindle for Z-probing the workpiece surface.

Since the isolator part between the electrode and nozzle is really tight you have to carefully drill it out till the electrode slides nicely in it.

I also soldered a small screw into the nozzle so that the point of contact is just a realloy small point.