Boatcraft does mail order. It is much easier to work with raw carbon/fiberglass weave than have to deal with rigid panels. Cutting composite panels can get messy and leave you with subpar results. Raw cloth can easily be cut with heavy duty scissors (just use wide masking tape on the cloth, front and back, and cut it down the middle. It also creates MUCH LESS dust which is a respiratory hazard as well.

If you're looking to give shape to your project, and not use the panels as structurally stressed members, then maybe look at Dacron cloth. You lay it over your frame, affix it at the edges, then take a blow dryer to it to shrink it over the frame. You can try a heat gun, but practice first. Dacron shrinks at around 225-250F, and melts at about 425F. Maybe a used Clothes iron from Value Village would be a good idea as the heat is easily adjusted and low enough. Don't use your significant other's or mother's iron.

Once it cools, you paint it with some epoxy and it seals it up. This is how skin on frame kayaks are made. It will end up much lighter than using fiberglass and look much better as well.