Exterior plywood will be fine if you border it. My neighbor took regular plank lumber and sawed it to the width he wanted and put a border on the quilt block front and back, although just the front would have been fine. He also sealed the plywood after painting with several coats of exterior sealer.
Last edited by QuiltnNan; 02-22-2014 at 06:20 AM.
Reason: remove copyright picture