Abstract: A foam sheet comprising a cellular structure having two or more interconnected cells in fluid communication with one another, the foam sheet being in the form of a tray. One or more perforations are provided in the exterior surface of the tray, and extend into the cellular structure of the foam sheet to fluidly communicate with the interconnected cells. This arrangement is sufficient to permit gas to escape from the cellular structure in order to substantially prevent damage to the tray upon exposure thereof to a reduction in ambient pressure. A method of making the trays and a packaging method employing such trays is also disclosed.