- M8, 2mm inductive sensor (5V)
- M12, 4mm inductive sensor
- M16, 8mm inductive sensor
- M16, adjustable distance capacitive sensor
- M16, 20mm capacitive sensor
- David Crocker's IR sensor
- SHARP analog sensor
The conclusions were:
- If you have an aluminum bed, I'd go for the 2mm inductive type
- For a glass-only bed, the BLTouch is a good option
- With a PEI sheet or other stick-on bed surface, David Crocker's differential IR sensor is also a great alternative
- The capacitive sensors are too sensitive to use seriously, and the SHARP type is not precise enough.
- Inductive sensors with larger trigger distances also work really well, but will need circuitry for adapting to 5V and are much larger than the 2mm type.
Detailed report with many interesting details can be found at: