Elmer's Black Foam Boards. Lightweight but strong and rigid to resist denting and crushing. The resilient polystyrene core bounces back after cutting to keep the board uniform edge to edge. The smooth surface satisfies a wide range of mediums including markers and paint. These foam boards are ideal for crafts, school projects, framing and mounting. Includes 25 sheets. Each foam sheet, 30" x 40", 1/2" thick.