Can't find the article but I read that during the cold war US used translucent resin with pieces of aluminium foil to seal high-security rooms, with multiple photos from different angles to capture the 3d arrangement of the foil.
A similar technique exists for non-replicable unique tokens. The token is multiple translucent microspheres pressed together and its authenticity verified by shining a laser on it from different directions and capturing the output.
A similar technique exists for non-replicable unique tokens. The token is multiple translucent microspheres pressed together and its authenticity verified by shining a laser on it from different directions and capturing the output.