I use Multicomp filaments a lot for my prints. Some of these filaments come in cardboard spools. As the spool rolls on the spool holder, its central hole gets damaged and cardboard shavings land on the printer. This adapter can be inserted into the hole in the centre of the spool to prevent this.

Print two copies and insert one into the hole on each side of the spool.

I have designed this specifically to fit the Multicomp filament spools (as pictured). It may or may not work for other spools.