Abstract: A dual compartment sandwich package fabricated of foamed polystyrene or the like and adapted to retain therein in appealing and acceptable form a sandwich including a hot meat portion, such as a hamburger, and a cool trimmings portion, such as lettuce and tomato. The package includes a base and cover having central rib means for rigidifying the package and preventing bending about the longitudinal and transverse axes thereof. There are four cooperating slots and tabs for temporary or secure locking of the cover to the base, which latter condition also forms an external seal to prevent heat exchange with the ambient atmosphere, while the central rib means form an internal barrier to prevent transfer of air and heat between the two compartments. A method of packaging a hot meat portion-cool trimmings portion sandwich, such as a lettuce and tomato hamburger sandwich for dispensing and final assembly by a customer in such a dual compartment package is also disclosed.

Abstract: A thin gauge plastic cover having a downwardly depending, outwardly flaring side wall the upper portion of which is integrally joined to an annular top. The cover top has a plurality of combination ventilation and finger holes. The cover is also provided with a lower arcuate locking rim provided with a plurality of cut-away portions to allow the rim to expand in diameter when it is locked over the periphery of a circular plate. The cut-away portions of the locking rim also expose portions of the plate rim to permit manually restraining the plate when the cover is being removed from the plate.

Abstract: A method and apparatus for producing apertures such as ventilation holes and the like in a preformed sheet of polystyrene foam which comprises forming slits which extend completely through the foam structure, the slits being arranged in a predetermined pattern, and passing the preslit foam through a heating zone such as a preheat oven used in plastic thermoforming operations. The resultant heated sheet of foam, as it emerges from the oven, is characterized by having a plurality of openings or apertures in locations corresponding to the slits which were made in the foam prior to preheating. The aperture containing sheets may be subsequently subjected to a thermoforming operation whereby thermoformed objects such as produce containers are produced having ventilation openings, i.e. apertures, located in a predetermined disposition around the thermoformed tray structure.