This is a mount for David Crocker / EscherTech's (https://miscsolutions.wordpress.com/mini-height-sensor-board / http://www.escher3d.com/) mini Differential IR Height sensor (also known as the DC42 IR probe).
It's a remixed version of https://www.thingiverse.com/thing:2700601 (IR_Sensor_Mount_Rear_v1.stl) to fit the extruder carriage of a Geeetech Aluminium Prusa i3. I've made a slit for the screw holes so it should fit M3 screws separated by a distance of between 25mm and 31mm. I've also shortened the length of the mount so that the sensor is closer to the rear of the carriage plate.
The sensor board should be fitted to the mount with M2 nuts and bolts (the nut should slide nicely into the vertical extrusions at the back of the mounting for the sensor board). The design allows for adjustment to the height of the board should different nozzles be fixed to the extruder.
To get the height required I lowered the nozzle to touch the bed, mounted the sensor board loosely and raised it by 10mm. I then placed a blank PCB underneath the sensor board, lowering it again onto the PCB in order to raise the sensor board away from the lowest point the nozzle could touch the build plate. This also gave a specific measurement that I could use to calibrate the sensor board
Geeetech Aliuminium Prusa i3