Outwater Plastics 1936-wh White 1 x 7/64 (.100)-in Thick Styrene Plastic Even Leg Angle Moulding 36-in Lengths in the Furniture Moulding department at Lowes.com
Amazon.com: 2pcs 1mm x 7.87" x 9.84" Black ABS Styrene Plastic Flat Sheet Plate : Industrial & Scientific
ABS Styrene Plastic Flat Sheet Plate White&Black Mult Size And Thickness - AliExpress