Well you see, my cat took the food, then completely re-engineered it, then returned it for my viewing pleasure. I'd call that a hack.
Puns aside, this is a cool trick and is the same concept of how an etching machine works. The only difference between etching and "marking" something is the type of current used. If you use DC current it will only eat away metal in one direction, making a pitted logo. If you use AC current, then it will eat away some, then put it back, eat away some, then put it back; causing a build up of metal and making more of a raised logo. Etching is more permanent than marking of course, but some people like the look of a mark better. That being said, I wonder what kind of hack one could do to make AC current safe enough to do marking at home on a budget? Personally I'm just going to get an etching machine that can do both very soon, so hopefully the only hacking done around here will be from my 2 furballed friends.