I use a metal stamp that I ordered, I know I saw pics where someone else dismantled one of the craft store paper punches and used that for stamping soap, and I'm pretty sure a couple people are using regular rubber stamps.
I stamp mine not long after cutting, when they're not too soft but not rock hard yet, and usually use a little gold mica on the stamp.
That's AWESOME!!!!!!!! But I don't see how a rubber stamp would work.......I was thinking of having a stamp made at an office store to use, but I don't know how to do it. A metal one would "cut" in in a sense and that I understand. Has anyone used a rubber stamp?????