Roseburg 3/4 x 4 x 8 Sturd-I-Floor Fir Tongue & Groove Plywood Subfloor at Menards®
Amazon.com: Baltic Birch Plywood, 6 mm 1/4 x 12 x 24 Inch Craft Wood, Box of 6 B/BB Grade Baltic Birch Sheets, Perfect for Laser, CNC Cutting and Wood Burning, by Woodpeckers :