[Editor's Note: There used to be a post here about some Escher-esque molds for creating tessellating gecko-patterned paving stones out of concrete. The creator of the molds got all 20th century (19th century?) on us and demanded that we take down the post (something about needing to negotiate a contract and cut a deal before publishing anything on the Web). We've removed all direct references to his product, but left up the post to retain the comments. We apologize for the inconvenience.]
Props to Steve for submitting this.