Bolt holder for Z endstop on Printrbot Jr

A holder for the bolts that holds the Z endstop screw in place on the Printrbot Jr. The screw kept loosening and the bottom bolt rolled down, so I made this little holder ting. Seems to work just fine (although it could - should - be tighter around the wood). Also eliminates the need for a wrench when adjusting the screw.

Welle417 made a tighter version - you might want to print that in stead: http://www.thingiverse.com/thing:82896