Developed by the Graf­fiti Research Lab a divi­sion of the Eye­beam R&D Open­Lab, LED Throw­ies are an inex­pens­ive way to add col­or to any fer­ro­mag­net­ic sur­face in your neigh­bor­hood. A Throw­ie con­sists of a lith­i­um bat­tery, a 10mm dif­fused LED and a rare-earth mag­net taped togeth­er. Throw it up high and in quant­ity to impress your friends and city officials.

via instructables.com