one of the toughest/weirdest jobs i ever did was engrave a bull elk on the objective bell of a Burris scope. it was going to be black anodized, so i had to cut the 'white' lines while it was still bright polished aluminum and the engraving would be filled with white paint after coating. i essentially had to cut a negative image. as if that wasn't a big enough pain, the anodizer ruined it and i had to do another one.
like engraving in a reverse universe...