Simplest Spool Holder

The original spool holder did not work very well. Therefore, I would like to make a simple and smooth spool holder for my 3D printer. The key is simple-easy to design, easy to print, and easy to assembly.

Note:
1) Need to print each part twice.
2) Need 4 ball bearings-outer diameter = 16mm, inner diameter = 8mm, width = 6mm.