I thought about that. We’ve had the ol’ yoga balls (which used to be just physical therapy balls) in the house forever. My grandmother was into yoga, they used them for my physical therapy when I was 3-4 yrs old at the cerebral palsy center, and even now there’s one rolling around here somewhere.
Back when I used to have a goat, when the ball would get kinda old, I’d throw it into the cage and he’d have fun with it, bouncing it around, trying to stand on it, falling off.