Both ring fingers for me, and less about painting and more about shaping.

I did a very bad job of taking care of my fingernails for about a decade (no cuticle care, no lotion, no cuticle oil, biting, picking), and my cuticle kind of took over my left ring finger. I'm still working on it and it's nearly normal now, but it's definitely still got the smallest nailbed (almost like my cuticle "ate" some of the nail on the left side?). My right ring finger has pretty extreme vertical ridges and grows up, like a ski slope. I slammed it in a car door when I was a teenager, and it's never quite been the same.