 Sign companies developed a new type of signage called channel lettering, in which individual letters were fashioned from sheet metal.While the market for neon lighting in outdoor advertising signage has declined since the mid twentieth century, in recent decades neon lighting has been used consciously in art, both in individual objects and integrated into architecture.Frank Popper traces the use of neon lighting as the principal element in artworks to Gyula Košice's late 1940s work in Argentina.