As far as buttons, search for 8 liner or cherry master.
Usually, the covers can be removed so you can insert labels on top of the diffusers.
I just got some in the mail. I popped the cover off one to see if I could do it without marring anything (barely).
You have to wedge something sharp down in next to it and tweak it.
Other than that, I have no experience with them. Gonna make a template and experiment with regular paper and ink-jet transparency labels this weekend.
(they are going in my driving cab as view & radio buttons

)
There are also some older touchscreen games in MAME too, but I haven't heard if anyone has had any luck with them.
I have a little 12" touchscreen running off a Megatouch board that it wouldn't be hard to hook up to my MAME computer and try, but I've never gotten around to it.