Nice idea, but there is nothing in nature as regular as these. There have been a few academic studies of likely stamps, and some attempts to reproduce them. A couple of them seem to have met with some degree of success, but they are not totally convincing to me. I have just discovered that I can cut three lines per millimetre with a Stanley blade in wax, but the blade is, of course, not removing any material.

Time for a new thread, to see if anyone has any ideas...