Fake Frost and Window Crystals

Saw this fake frost on the store windows at a Bass Pro Shop today.  I do not know how it was made, but it shows pretty crystal patterns.  For comparison, the van windows have real frost.  One can saturate water with Epsom salt (magnesium sulfate) and paint the solution on dark-colored paper.  When the water on the paper dries, the white salt crystals look like frost. When I was a graduate student some twenty years ago, I would occasionally work with organic compounds that melted at temperatures not far above room temperature.  Sometimes a flask with a film of this melted liquid would cool in my hands.  As the film solidified, pretty crystal stars would form along the walls of the flask.  This was always fun to see.  Update on 6-4-13:  today one of my kids got some Crayola Crystal Effects Window Markers.  When the marker ink dries it makes pretty crystal stars.