This is a quick hack sensor mount to fit an LJ12A3-4-Z/AX proximity sensor to a CTC Bizer Replicator clone, for automatic bed levelling.
It won't suddently make your CTC capable of doing levelling - it's not possible with the stock mightyboard. It can be done if you convert to other electronics and run marlin (that's what I've done), or, if you change to a mightyboard with an atmega 2560 and use the right build of sailfish (apparently).
It mounts by replacing the spacer for the left hand screw for the left hand extruder, and you use a longer screw up from the bottom, replacing the original one that holds the extruder bar onto the carriage.
Because there is not really room for the sensor on the CTC, putting it outside the edge of the carriage like this needs the soft end stops (travel limits) to be reduced to stop the printer ramming the sensor into the left hand x axis mount.
PLA is ok, it's not that close to the extruder nozzle.