Cool! My grandma and great-grandmother were professional quilt makers for upscale families in Louisville, KY, many years ago. Some of their personal quilts have lovely applique, but I never knew how it was done. Thanks to your illustration, now I do!

I love this idea because it is always so hard to find an appropriate belt. I'm thinking of experimenting with 3-4 times the waist measurement. If the cords are each marked with a thread at intervals according to the waist measurement (i.e. 26" waist, so mark a length of cord every 26 inches before braiding), when it is finished that should give me an idea of how much cord would be needed for future projects.
As far as buckles go, you can look online, but I went to different thrift stores. Belts go for very little, and while you might not want the belt, the buckles are often different than any you can find in a notions store and often in very good shape.