I’ve seen a few of these tiny (maybe 4 inches by 4 inches) instillations all around Fishtown and NoLibs just mounted on walls. Not really too sure how they’re doing it (gum?), but I think it’s pretty creative.

UPDATE: These little creations are the work of Chris M. Clark, and lucky for you he’s got an art show opening September 24th through October 22nd at the Stupid Easy space in Old City (307 Market Street above Artist & Craftsman Supply).