Ender-3 Spool Adapter

Updated Jul 13, 2020: Fixed spool_holder_left.stl to have the proper version, not just a copy of spool_holder_right.stl.

This is an update to one of the first things I created when I got my Ender-3. This refinement covers spools with smaller and larger hubs. Fits spools with inner diameters from 50mm to 74mm.

To ensure fit, print the retaining ring and fittest first to test your configuration