I haven't yet sewn mine just yet, but I can tell you how I cut mine out.
I have two strips that are 4 inches by 18 inches. Extra length ensures I won't have a too close call for my waist ( and it's always easier to cut away than trying to stitch back on that one dang inch!) The actual rolls are two pieces that equal 36 inches long as well by 10 1/2 inches wide. Why did I pick 10 1/2? Because that's what I had to work with for even cut blocks of goatskin. If you think you need wider, go for it!
From everything I can tell, the actual rolls are different sizes, the first one is the largest and it gets
slightly smaller down. If someone is absolutely sure it's different, please give us all a measurement?
When you've sewn this together, my best estimate is you'll have a 3 1/2 wide cummerbund. My mom is a really good seamstress, and though I'm working the leather stuff, I'm waiting for her to get a chance to come by to help me install a zipper in the vest and help me figure out how to sew these rolls on the cummerbund. That's about all I got. I will say that I've read, numerously, that much that is made is custom fit, which means a really tall, bustier Amazonian woman would need a different measurement than a short, elf-like person. I guess that translates to widen and narrow it as needed according to your waist.