Stable, Adjustable-Width Spool Holder Using 608 Bearings

UPDATED WITH A MORE ROBUST DESIGN HERE: https://www.thingiverse.com/thing:4068978

This is a snap together filament holder using four 608 skateboard bearings which can be found on eBay for less than five dollars for a set of four, sometimes eight bearings. It's adjustable with the sides staying parallel. I've used this for over a year and have found it easy to use and reliable while reducing filament tension dramatically.

Has fit every spool I've thrown at it from the tiny M3D spools to the