Low profile filament spool holder

A low profile - 2 mm clearance to bottom for 200 mm spools. Requires 4x standard 608 bearings.

Included FreeCAD model has parameters that should be adjustable for different sized spools.

This was inspired by the TUSH (The Ultimate Spool Holder, https://www.thingiverse.com/thing:2047554) and the mini TUSH remix (https://www.thingiverse.com/thing:5400974).