Printrbot Simple Metal Bed Sensor Nut

The goal of this set of things is to improve the way the inductive bed sensor is held in place

Thing 1: A long nut that holds the sensor in place. Allows easier and more accurate manipulation of z-sensor height from bed.
Thing 2: A smaller nut holder that takes the existing nuts and makes them easier to manipulate by hand

test_nut - this is the first test file to see what fits with the sensor. generated with openscad