Central filament spool axis with bearings.

I've seen many of these around but haven't got 100% satisfied with them, so I designed my own version.
It's very useful if you want zero friction on your spools. This fits with almost all common 1kg spools.

It fits spools with internal holes from ~32 - 65 mm.
I assembly it using common 22 mm bearings.

Print instructions

Print threads on Z axis (kind of obvious).
Using 0.2 mm of vertical resolution is fine.
Supports for the bottom bearing slot are recommended.

2020-04-28 Update:

• New version added: Axis 100 mm long