a sterilization tray is constructed primarily of a single stamped metal part which forms the bottom wall and at least two opposite side walls of the tray . the side walls of the tray are joined by end closures which form the end walls of the tray . in one tray embodiment , the end closures are plastic end walls which are hooked to the ends of the side walls . in a second embodiment , the end closures are formed by a bottom wall extension of the metal part which are folded up to form the tray end walls and plastic corner pieces which are hooked to the adjacent ends of the side and end walls . the tray is highly thermally conductive yet relatively inexpensive to make in quantity .