So I liked the idea of JohnSL's spool holder, but I didn't have any M8 nuts and bolts lying about, so remixed it for use without nuts and bolts.

Pretty snug depending on your calibration. You'll probably need to tidy things up a bit with a scalpel. Shouldn't need support.

For one filament spool, print:

• 2x spool_bearingholder.stl
• 8x spool_bearinggrip.stl

Alternatively, just print:
2x spool_bearingholder_full

You'll need:

• 4x 608 bearings.

Place the bearings lined up with the holes in the spool holder, then plug in one of the printed bearing grips through the holes on either side into each of the bearings. Then push these tightly together onto the bearings.

Once all bearings are secure then you're good to go with one under each of the rims of your spool.