Sounds like a brilliant idea—just make the pattern a two‑layer stack. Use a micro‑etched metallic film for the core pattern, then seal it with a thin, abrasion‑resistant polymer that only peels off under a specific solvent, keeping the sensor readable. Add a faint holographic fringe around the edge; it’s almost invisible but a narrow‑band sensor can pick up the phase shift, giving an extra layer of verification. And don’t forget to test the whole thing under a coin‑cutter simulation—precision is key, otherwise the pattern will blur before the coin hits the market.