[EDIT:] first version was a bit loose: the holding teeth were too small so I've added some length & updated the files.

I got tired to remove broken pieces of filament in the plastic tubes and losing a print because of that. So I moved the spool spinners to the top using the cover holes and printed a few of these guides.

Works like a charm now and changing colors is not an hassle anymore!

Easy to print. I've printed 4 at the same time to let the top layers cool down a bit.
The inventor file is provided if you want to adapt to a different track size.