I had difficulties printing similar models and I noticed that my cat liked the unfinished print. I created this model with a large opening so your pet can paw at the small inner ball. No need for supports.
Updates:
I recommend the remixed threaded cat ball.
I revised the brimmed version to include a brim for the inner ball. The brim is additional geometry that is easily removable inside PrusaSlicer if you don't want it.
The author marked this model as their own original creation.