I've built a few tombstone and they come out pretty good but not as "clean" as the ones I see other people do. By clean I mean my letters can have some pretty rough edges, never a very "crisp" lettering. I use a dermal tool with bit and have tried a number of different bits like regular drill bits and once a sheet-rock bit which I think worked pretty well. I need a new bit and was wondering what bit y"all use and how deep do you carve the lettering? I mostly use the blue foam for my stones and here's a picture of a a cemetery sign I made late week to give you an idea of what I mean.