Minimalistic filament spool holder small footprint 4 OneUp / Printrbot etc.

This filament spool holder has a diameter of 43mm and a max. footprint of 60x60mm. It can be used with an extra ball bearing. I took one from a bicyle. It is very small and easy to slice, print or modify.
In case you need more grip use double sided adhesive tape underneath. Then there is also an adapter with a diameter of 48mm to 43mm. The 48mm was found using Sainsmart filament spools. The thing is very uselful for spools like the one from Sainsmart, that have very bad spools (like cardboard)