I wouldn't separate anything. This box screams crazy quilt to me. The more textures the better. Have you some decorative stitches on your machine? You can make use of those as well. An old worn light colored sheet works great as the foundation or some thin Muslim. Maybe you have some thin fabric in your box you can use. Google crazy quilts and the patterns are endless. I've made 2 and they were some of the most fun quilts I have ever made.