z home optocoupler mount for printrbot plus V1

it's a piece of plastic that holds an optocoupler, i found it inside a photocopier, i think they are pretty standard because i found a lot of them in different machines and they are all the same, so i made this to hold it in place. the wiring for this, in case of the printrboard consists in 2 resistors, one to power the ir LED and the other as a pullup for the phototransistor.