I'm honestly thinking that clear buttons should be on the list. I have it on my list to ask casters, "Do we get the colors by adding dye to clear plastic? If so, can we run off a bunch of clear sets?"

That way maybe people could modify them (like you and Skunk mentioned) to get those cool effects or colors of their choice. Maybe people could color the "back" surfaces which don't come in contact with their fingers. Then maybe the light could shine through this exterior color and maybe push it throught buttons.