Ok, so I was inspired by Zaggo’s two excellent probe designs: http://www.thingiverse.com/thing:4226And had started making both of them at various times. I’d finished making his minimalist probe and realised that i’d have trouble mounting it on my bot. (I’ve got bot number 3, and it doesn’t have that nifty ‘U’ cutout from the acrylic that the newer ones do.) There was no way to mount them that close to my extruder without running the risk of melting or fouling against it.Then i got to thinking, the reason (I presume) the probes were put on a servo is that you want to be able to get them out of the way of the object being printed.But as long as the lowest thing on the Z axis is the nozzle (by at least a few mill) you’re set, right?With that in mind I decided to try mounting a little microswitch to the underside of the Z-plate, and have it home when the platform’s at the most Y+ end. The extruder tip clears the side of the platform with room to spare, and the switch touches nicely agains the platform. (See pic)So far it's behaved extremely repeatably, and I'm now running prints from a single button click. (High fives everyone in the room!)Considering this uses a switch and some hot melt glue, I'm guessing this is the most minimalistic Z-probe you can get. :-DAnother advantage of this design is that you don't need to use custom firmware. Everything is taken care of by the G-code I added the following code to my start.txt:( Auto Homing Y&Z Routine ) ( Use only if you\'ve got Y+ and Z- limit switches installed ) ( Only works if tip within 50mm of build surface!!! ) G91 (relative Positioning) G0 X0 Y150 (move Y axis to its end stop) G0 Z-50 (lower Z until hits limit) G92 Z0 (Set current point as Z-origin) G0 Z15 (raise Z above table to clear) G0 X0 Y-65 (move build platform to middle of table) G0 Z-4.1 (touch the table) G92 X0 Y0 Z0 (Set current point as origin) G90 (switch back to absolute positioning) ( End Auto Homing Y&Z Routine )Note: There's no feedback to the motherboard when the axis has hit it's home. It simply stops the motor. That means that if you do a Z move to -100 when you're 10mm away, it'll take the full length of time until the next move occurs. That takes way to long for my impatient blood, so I've set it to do a -50mm move, and I'll just have to remember to only press print when the tip is reasonably close to the build platform.