STYROFOAM R-4, 0.78-in x 8-ft x 4-ft Residential Sheathing Faced Polystyrene For Use In Garage Doors Board Insulation Sound Barrier in the Board Insulation department at Lowes.com
Expanded PVC Sheet Lightweight Rigid Foam 6mm (1/4Inch) 12 x 12 inches Black Ideal for Signage, Displays, and Digital/Screen Printing - Walmart.com
Insullam Insulation Board, 11-1/4 inch with 7/16 inch OSB
PVC Foam Board - White - 1/4 inch thick - various sizes – Herzog Group
Amazon.com: Expanded PVC Foam Board, White, 1/4" (0.25", 6MM) Thick, 18" W x 48" L : Industrial & Scientific
Foamboard - White/White - 4' x 8' x 1/2" - Set Shop NYC