Screw Invisible Ink.

Brooklyn based designer Reiner Tiangco has created a unqie kind of art that requires some one-on-one attention in order for its message to be revealed. He calls it the "Dirt Po(or)ster". In fact, Reiner claims that the poster isn't really finished until you put your hands on it - which is a really cool twist to buying art. More than just the purchase, it's an organic piece that the buyer can dismiss, contort, create or finish. He says it's the first of many to come.