Fabric stores are better sources of cloth. For one thing, you can actually look at a range of different weights and see the differences.

Keep in mind also that the thickness of the cloth determines to a large extent the finished weight of the airplane. All our composites gain their strength from the fibers being rigidly bound together, and their weight from how much glue is required to do that. When the cloth is thick, you get unnecessary weight.

C/L stunt has used fabric store cloth from the beginning. For finishing purposes, if you feel the cloth is too thin, it's just about right.

One trick to using it is to paint it on with polyurethane paint, not use epoxy or fiberglass resin. It won't be quite as strong overall, puncture resistance for example, but will give good structural help, and will be adequate for models.