Greetings Who,
I've looked up Blockade runners and I assume yours is like the attached?

That being so, you only have two "gaff" sails to create. Depending on your scale, I would use either a white thin cotton hankerchief, or section cut from cotton shirt or cheap cotton pillow case etc. You want unbleached material if possible. A quick folded hem around the sail edges using pve glue would work nicely. Once dried stitch onto masts with a spiraling stich, then haul all in tight to the mast as if the brails had been hauled taught. To keep gathered at the mast tie some robands equally spaced.
Looking at the image posted, there is now reuirement for it to be folded in nice and neat.
Kimosubby.