 It differs from older techniques which all produced only enamel on a flat or curved surface, and mostly, like champlevé, normally used non-precious metals, such as copper, which were gilded to look like gold.In the technique of enamel "en ronde-bosse" small figures are created in gold or silver and their surfaces lightly roughened to provide a key for the enamel, which is applied as a paste and fired.In places the framework may only be wire.