You can raise the top irons and pin an old bed sheet on it to make a pattern. Muslin would likely be better but you get the idea. Look at photos to see where they are reinforced and where sections may be overlapped or valanced. Some folks like to customize the style like the little blue 29 that Mike Bishop & Vern Tardel built for their traditional hot rod book.
Get some books on the subject & watch any videos that might be available. Kits make life easy but if you want something different then go for it. This is one video that will give an idea of what's involved with pads, reinforcements, and the like.
https://www.youtube.com/watch?v=jT2B7rVmoCA