Cellofoam Flexible Foam Packaging: Copolymer In addition to Cellofoam's exclusive line of expanded polystyrene (EPS) foam packaging products and materials, we also produce a line of corrugated shipping alternatives (think cardboad) in the form of flexible foam packaging, made from a variety of plastic materials, including copolymer resins. For those that are unfamiliar with copolymer, it is a highly durable and incredibly versatile plastic that is used in a variety of applications, including custom packaging, roadway construction, and more. It offers many benefits including low-cost, high durability, cold-temperature performance, and heat resistance, making it a truly great shipping option.