Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4760817.

Because my printer can print a max of 18cm in z direction and the spools I buy are bigger as normal spools I had to produce an adapter/extension to make the 30cm diameter spools fit in https://www.thingiverse.com/thing:3823334 from les_kaye. I attach them with those strong clips that hold a glass plate firmly on the bed. Enjoy. Update 14 feb 2021: Edited tolerances for better fit.