I believe that the available probe options that are working today are:
Neither of my printers have been stable enough to get repeatable results using Holoped's original probe or FSR's, so I cannot comment on the functionality with any of these options.....
- Allen wrench, as on the Kossel.
- Force Sense Resistors (FSR), using JohnSL's adapter board, an Adafruit Trinket, or wired to your controller.
- AndyCart's Cherry Pi III effector, using a switch and hinged hotend, based on Holoped's original design.
- Various proximity sensors being tested.
Neither of my printers have been stable enough to get repeatable results using Holoped's original probe or FSR's, so I cannot comment on the functionality with any of these options.....