Oh! Making one is a good idea! It's all about what your cat likes, and you can never have to many cut cat products!
I would want one with a cute design! 😁
And yeah. I've never had a cat with kidney stones, l luckily. But I've heard it's really painful, especially in boy cats. A family I babysat for had a cat that was nearly 20 years old and she had kidney stones a few times. But luckily the mom was a vet, so she could treat her asap! (That's also probably why the cat lived to long! She was an amazing owner!)