PVC Foam Board - White - 1/4 inch thick - various sizes – Herzog Group
16 Pack Foam Board 11.7x16.5 Inch, CBTONE 3/16 Inch Thick White Polystyrene Foam Sheet for Photo Framing, Art Display and Handicraft - Walmart.com
White Daler Foam Board 5mm thick | George Weil
White PVC Sheet Foam Board Building Model Display DIY Craft 2/3/5/7/8mm Thick | eBay
11x14 Elmer's Foam Boards
Amazon.com : AKOLAFE 30 Pack 10x8 Inch Foam Boards, 5 mm Thick Foam Core Board 1/5 Inch White Foam Sheet, White Polystyrene Poster Board Signboard for Presentations, School, Office & Art Projects : Office Products