Distrack3D made a great little cat toy with a satisfying wobble that my two weirdos took to immediately, and I threw together a few files to make it even better! The biggest issue was that it tips easily, which can be fixed with a wider base.

There's multiple plates in the 3mf:
1 - Saucer that fits right over the original round base, makes it very stable. Great if you printed the original already! Rubber feet on the bottom of both parts helps even more.
2 - A new voronoi ball! It's fairly easy to knock treats out so it's great for when both my cats are interested. Everybody wins!
3 - Original ball from Distrack3D with a couple of the holes merged. This makes it so treats can fall out but it's not nearly as easy as with the Voronoi ball. If you need to, it's easy to snip a small section to enlarge the hole a little bit more. This is great for keeping them focused for a while.
4 - Saucer merged with original base plus the wobble stem. With this you shouldn't need to add weight unless your cat is a giant beast.

For the balls, use the included manual supports that are painted on - they need supports, and automatic supports fill the entire object with supports. I suggest 0.16 layer height for these, and overhang speeds are slowed way down. Everything does work fine at 0.20 layer height as well.

We need more cat toys! If anyone comes up with new toppers for this or other toys, please share. My cats can never get enough novelty.