I have already tried a couple of foam type materials for this purpose. They didn't last very long, they lost their cushioning effect and went flat after a while. What type did you have success with? What have lasted for me is plain furniture felt pads, the thick sturdy type. It's sold various places, easy to find, and doesn't cost much. I have even tried a foamy type furniture pad with grip and anti-slide effect, made for the purpose, but it turned flat after a while.