The Pasta Lite respooler by @KYZDesign is absolutely brilliant. Unfortunately, it only allows respooling onto empty spools with smaller diameter holes (like the stock Bambu reusable spools). I had some other spools laying around  with larger diameter holes that I wanted to use but the stock spindle was far too small.

These rings are intended to allow the use of a wider variety of spools. Center one on each side of the spool and attach the spindle as usual. It's OK if the inner ring doesn't match up exactly with the spool hole. Just make sure the spindle is on tightly.

This adapter will also fit on the Donor Spinner spindle.