Are you suggesting you've successfully achieved unbreakable physical security?

When you engrave characters to metal, this changes the metal's shape, making the characters clearly readable with pretty much any sort of reflective radiation.  The tamper proof case may look great but what if tampering is unnecessary because any physician can take it to work and see through the case with medical imaging gear?  An engraved secret in a metal coin is also going to be vulnerable to magnetic imaging techniques.


Not even the maker of the coin?