G2S Magnetic Cup Adapter

This is another request (sort of). It is a version of my [Magnetic Rod Adapter](http://www.thingiverse.com/thing:1668977), modified to take the commonly available 12mm diameter magnetic cup style ball joint.

PLEASE NOTE: I do not own any of the magnetic cups to test this design. If you encounter any problems, please let me know so I can correct it.

UPDATE: Made it a bit less bulky to be easier to set the optimum angle without interference from surrounding parts.