Foam-core

A strong, stiff, resilient, and lightweight board of polystyrene laminated with paper on both of its sides. It may be any of several thicknesses, in any of a variety of colours. It is often employed as a surface on which to mount two-dimensional work, and as a material with which to construct three-dimensional work (such as architectural models). Although more expensive than some other cardboards, it is preferred to them for many qualities, including the ease with which it can be cut.

Make straight cuts by using an extremely sharp razor knife on top of a mat or other surface that will not be damaged. Draw the knife toward you along the edge of a metal ruler (with finger tips away from that path). Cuts at each of three successive depths will produce a neat edge to the board. (Artlex.com)

Canadian Heritage University of Regina Mackenzie Art Gallery Mendel Art Gallery Sask Learning