Artist Daniel Bejar had a key copied and then a new key copied from it, and so on, until the information embodied in the original key had been lost. He calls the resulting piece "The Visual Topography of a Generation Gap": "A copy was made from my original apartment key, then a copy was made from
that copy. This process was repeated until the original keys information was
destroyed, resulting in the topography of a generation."
"The Visual Topography of a Generation Gap"(#2, Brooklyn, NY)
(Thanks, Fipi Lele!)