Amazon.com: Flipside Products - Large White Foam Board, 30" x 40", 10 Pack, 5mm Thick : Office Products
Amazon.com : Union Premium Foam Board 30 x 40 x 3/16" 10-Pack : Matte Finish High-Density Professional Use, Perfect for Presentations, Signboards, Arts and Crafts, Framing, Display (White, 30x40) : Office Products