Improved M3D Micro Filament Spool Holder

This is an external filament path spool holder for the M3D Micro printer. I found that the internal filament path was just plain annoying, especially when needing to change the filament. This design is heavily inspired by ilikesanta's original version, however I've made quite a few changes:

• Tolerances on the frame clip have been tightened.
• Length of the arms has been increased slightly.
• The shaft has been completely redesigned.
• Attachment of the shaft to the arms is vastly simpler.
• The mount can be secured via clamping hardware.

In short, I wanted the shaft to sit loosely via gravity and not need to be locked into place. I also wanted the arms to be secure and not slide around along the printer's frame, but at the same time I didn't want to have to permanently modify (drill holes through) the frame.