Well I had absolutely no problems with the durability of the standard plastic material but you could print in metal which should hold up very good. If possible I sand the 3d parts with 1000grit paper because the structure which the 3D printed objects have is a bit 'sandy' and I expect then to get dirty when used as buttons.
I posted on a forum overhere if anyone would have a EX800 around for inspection but no luck as of yet. I will keep an eye out though.
Cheers,
Grit