I would start by putting them up on a design wall, look at them until I got them in the places I like them, then if they are straight cuts I would start sewing them together like a crazy quilt (stitch and flip on a foundation). If they are curves maybe you can just slowly begin sewing them together but this sounds risky. The simplest would be to piece a pretty background, maybe something like a colorwash, and then applique like you have the the past. Good luck, hope to see what you come up with.