A term designating works of art other than prints or cast sculpture that are designed to be produced in a large—potentially limitless—number of copies. Whereas prints and casts of sculptures are copies of an original work hand-made by the artist, multiples are different, for the artist often produces only a blueprint or set of specifications for an industrial process of manufacture in materials such as plastic. Multiples were first made in the 1960s, Le Parc and Oldenburg being early exponents. In theory, they represented a democratization of art, but in practice they are too expensive for a mass market and have usually been sold through galleries rather than high street shops. By about 1980 the idea seemed to be dying out, but there was a revival of interest in the 1990s.