The problem with making your own leaders, is that they're usually over 100" long. When we make leaders for the Grace frames, we buy a poly blend fabric that's about 54" wide, from a wholesale distributor, and cut about 10 sets of leaders from a bolt. You could probably get one set from 3 1/4 yd of 54" wide fabric. You can get two 12" to 18" widths from a regular width fabric. Then your take-up leader needs to be wider -- so it can go around the 5th rail. You'd cut that one about 24" to 28" wide. So you'd have to double that if your fabric was a regular 44/45" wide. Take a big pin with you to test the "needle" of the fabric. You want the pin to slide in easily. There might be something in the home dec. section of the fabric store that would work. It doesn't have to be white.
Then you need Velcro that's as long as your leaders, so it will attach to the frame. You can get a 25 yd roll of Duragrip (just the loop side) from HookandLoop.com for about $15 plus shipping.
Good Luck with your endeavor!