Foam-core is a great product to create mock-ups and architectural models or prototypes or use as a backing board to mount artwork. Foam-core board is easy to cut and shape with a Stanley knife or scalpel and a metal ruler and is available in a range of sizes. A fairly durable, extremely lightweight, rigid product of polystyrene sandwiched between two pieces of paper. Use it for sculptures, mounting posters, signs, wedding charts, packaging and the list goes on. The most popular foam-core board sizes are fairly standard from A4, A3, A2, A1 and 32" x 40".