I actually had no issue engraving on the Hershey’s bar. I created some .jpegs of different words like “Mine” “Not Mine” “Not Yours” in an italics font and really didn’t have to dial anything in to just print these right onto the back of the bar.
Playing with the settings a little didn’t really make that much of a difference, though I did keep the speed up towards the higher end of the spectrum as I didn’t want the laser to linger too much in any spot.
More complex designs I think will be a bit more difficult since I think you’ll want to have some rest time if you’re in close proximity.
Part of the reason that I’ve been experimenting on this cheap chocolate bar is that my wife does a bunch of cake designs and wants me to justify my purchase by being able to create engraved chocolate for accent pieces on her cakes whether it’s in some chocolate or fondant or whatever else she might want to have. In this I thought that creating the shapes directly might be interesting rather than creating molds.