Smallest Christmas card

British scientists have created what they believe is the world's smallest Christmas card, a seasonal greeting so tiny that over 200 million of them could fit into a standard postage stamp. The card, created by the National Physical Laboratory (NPL), the U.K.'s national measurement standards laboratory, measures 15 x 20 micrometers. A micrometer is one millionth of a meter. It is made from platinum-coated silicon nitride, and was illustrated using a focused ion beam. One of the card's inventors, NPL's Dr David Cox, who created the card along with his colleague Dr Kin Mingard, said the technology used in its making had more practical uses.