Bank notes

Canada now uses holograms on its $20, $50, $100 and $1000 bills. They're a small patch on the top right hand corner that looks like gold foil. Written on this foil is the denomination of the bill (20, 50, &c). As the viewing angle is changed, the color of this writing shifts. Obviously, this will blow a photocopier out of the water. I have minimal experience in holography, but it would also seem to be difficult to print one on a metal foil. -- PGP 2.3 Key by finger