Requires enormous skill:
The hardest features to forge with any level of sophistication are on the front of the note: the US Treasury seal, the large “100″ denomination in the bottom-right corner, and the united states of america at the top. Real US currency is printed on massive intaglio presses (intaglio is Italian for engrave). The force with which the presses strike the paper lying over the engraved steel plates creates indentations that fill with ink, giving the bills a delicate 3-D relief and a textured feel. Its absence is a telltale sign of a counterfeit. For [German artist and printmaker Hans-Jürgen Kuhl] this was the most critical puzzle piece: how to create that texture convincingly without the benefit of actual engraving.
The Dish 