Kossel Filament Holder

I was searching for a Filament holder that saves space and is compatible with every spool size. After some experiments I ended up with this solution :-)
The base of the filament holder is mounted to a top corner of the delta printer. The two rails can be slided onto the base plate in any position. The width of the base plate fits all spool sizes that I ever used (manufacturers should really agree on standard here).
The spool is mounted to two default skateboard bearings for each rail, ABEC doe