Ball has a small flat area on bottom for bed adhesion.
If you want to use a different ball, use the "No Ball" file, then drop in a ping pong or other ball once the print has proceeded past the height of your ball. Note, standard ping pong balls are 40mm diameter, so wait until you are at 41mm.
Requires a 300mm x 300mm print bed at this scale. Significant internal overhangs; would benefit from thin layers and multiple walls.
Please lightly sand the edges of the openings, so your cat doesn't cut its paws.
Edit it as you like: https://www.tinkercad.com/things/7xnUpXU5Jds