Adaptor for winding cones on an AVL bobbin winder

This is an adaptor for winding yarn on to cones using a double-ended bobbin winder like the ones shown in the picture. I've tested it on an older AVL bobbin winder, though I'd expect that it'd also work on Schacht or similar bobbin winders. If you test it on one of those, please let me know how it goes so I can update these notes.

Essentially, you print this part and then insert it into the bottom of a cardboard cone. This fills the wide end of the cone so you can fit it onto the bobbin winde