Foam Core Backing Board 3/16" White 1 Side Self Adhesive 24x36- 50 Pack. Many Sizes Available. Acid Free Buffered Craft Poster Board for Signs, Presentations, School, Office and Art Projects - Walmart.com
Amazon.com : Union Strong Foam Board 24X36 3/16" 10-Pack : Matte Finish High-Density Professional Use, Suitable for Presentations, Signboards, Arts and Crafts, Framing, Display (White, 24 x 36 x 3/16") : Office Products
Amazon.com : Frienda 20 Pcs Foam Board 24 x 36 Inch White and Black Foam Poster Board 3/16 Inch Thick Foam Core Backing Board Mat Board Center for Prints Presentations Signboards Arts
Elmer's Foam Board 3/16 x 24 x 36" | United Art & Education
8 Pack Corrugated Plastic Yard Signs 24x36 for Outdoor, Open House, Birthday, Lawn, Foam Poster Board with 4mm Blank Surface (Black) | Michaels