CNC utilizes contact probes for various purposes:
- Edge Finding
- Zero Setting
- Digitizing (point cloud)
Several major companies exist (example Renishaw) to service major industry; less so for home or prosumer markets.
Of late, two have captured my attention.
Kurokesu AKA Saulius Lukse from Lithuania (http://lukse.lt/uzrasai/) (two production runs have been produced so far, and a wireless variant in development):
and TouchExpress ( Cliff Hall from New Zealand):