I would use aircraft plywood, you can get it in most hobby shops in small pieces. It is very strong and made of many small laminations. I use the 1/8" size for fins on High Power rockets using motors up to J (350# thrust) If you put it together with epoxy it will work very well. I would think that the 1/4" would do well. You can also try www.balsausa.com
Yours, Dwight
