But the 60mm buttons might be too big. I did some measurements on the stool, and they will likely hang down over the front hole. Worse, four of them would be a tight fit across the front.
I wish there were 45mm buttons, or something. I think 30mm might be too small to hit with my toe without looking down to make sure I'm getting the right one, which kind of defeats the purpose.
I will keep looking for buttons. I'm usually in my stocking feet or barefoot, so stomp box switches would probably hurt.
UPDATE: As Santa Claus said in that M&M commercial they trot out every Christmas, they do exist!