Automatic bed leveling calibration

I have acctually wanted to try to paint a frame on top of my bed with conductive paint and use the nozzle to make a connection with a small current to set the zero.

My big issue is that i dont know the programming part, any ideas?

And for the issue with melted plastic on the nozzle, i have until now hold it clean and heating it up and cleaning it and then let it cool before setting the zero should not be a problem i think.

Say it heats up, i clean, and then initiate the zeroing, then it cools down and starting to set zero when the temperature is below 50c...?
BR

 

All the solutions for this have used switches which are mounted to a servo to move it up/down when leveling. The firmware already has support for it, so the programming part is done. There are plenty of designs on thingiverse which would be pretty easy to implement for the R3D if one were so inclined. One of the bigger issues tho is keeping the bed level across the X axis with the threaded rods. You'd probably be better off doing a ballscrew conversion or Y axis linear rail conversion to get better prints first than automatic bed leveling. $0.02.