This thing is a filament spool that holds about 250g. It is printed in two pieces that snap together. The two pieces can also be glued and/or screwed together. The model incorporates holes for optional 2.0mm screws if a super secure assembly is desired.

Note from the pictures (circled in red) that the two pieces will only connect at a single rotation because of the slot in the hub for the starting end of the filament.

Prusa

I3 MK3S

No

Yes

Supports are required for (1) the screw head recesses, (2) the recessed filament slots near the edges, and (3) the edge of the snap hooks. I checked the box "Don't support bridges" in the slicer so that the text would not be filled with support material.

This project was modeled in Fusion 360. I'll happily share the project to anyone interested.