Summary

Fidget toy. The balls are going through the track, and return to the the top for next loop.
Hold Vertically, with track enter on top of track exit (see photo).

No supports needed.
Print the 3 parts.
Insert 5mm bering balls into the track in the "main body" (not more then 8).
Insert the "main body" into the "ring".
GLUE the "cover" on top.
Once the glue is dry, move the outer ring slowly, so each ball will "find" his slot. after 4 - they will start to fall from the other side, use screw driver or something thin to hold it in place.

ENJOY

(need to buy the balls, such as : https://he.aliexpress.com/w/wholesale-5mm-ball-bearings.html?spm=a2g0o.home.auto_suggest.4.2e076278ELZZWs) .