A tray cabinet wherein each comprises a heating chamber formed between a shell and a detachable cover. A heating element is placed between the base of the shell and a shield. The shell has an edge embedded in the thickness of an upper plate of the tray. A dense foam fills the interior space of the tray...http://www.google.com/patents/US4235282?utm_source=gb-gplus-sharePatent US4235282 - Heating and refrigerating tray cabinet for distributing hot and cold dishes
