Rostock Max V2 Spool Holder Advanced

This is a remix if knabo's well designed spool holder for the Rostock Max V2.
I didn't like some details of the original design, so I re-designed the entire thing.

The changes are:
- less ball bearings required
- less parts to print
- easier assembly (just one screw)
- M8 metric screw instead of 3/8 inch rod

Non printed parts required:
2x 608 ball bearings
1x M8 threaded rod, approx. 135mm long
3x M8 washer
2x M8 nut (2 regular nuts, or 1 regular and 1 cap nut)