I tried to print several of these styles of cat toy in the past using a model from 2012, but they have been difficult to print for one reason or another. I figured I'd make a customizable version that you can adjust the dimensions with and release it.
Printed one at the default 40mm size, came out pretty nice. I'm interested to see what other sizes folks make. Going small and large could prove to be a serious printer torture test based on the overhang angles. Enjoy.
Generally I'd imagine it's best to generate support structure for the bottom to achieve better adhesion to the plate and once done, break loose the support and inside ball.