Rocketeers Store has Fiberglass Sheets recommended for manufacture of rocket fins.
The sizes vary both for compression/length ("side", in cm) and for thickness (in mm).
The use of the product must be done by experienced people. A Rocketeers Store is not responsible for incorrect, inappropriate use or in disagreement with the norms and laws.
Illustrative image of the product. Differences in the packaging may exist for a better conservation of the product.