Being impatient, I tested it on some polymer clay:
Unlike wax, the clay remains soft so it deforms a bit while removing the stamp.
I think the "scroll" part is too deep, so the text doesn't reach the wax (or fimo, in this case). The "shields" are a bit on the deep side as well I think. But the general idea looks okay. The resolution of the steel isn't so great, more expensive materials allow finer detail.
