The patchwork pieces I have seen (in person) made from felted sweaters have mostly been blankets and throws, made with no batting, no backing, no binding and no quilting. They are beautiful, soft, and warm. The patches are butted up against each other, not overlapped, and zig-zagged together. The back and the front are identical. Sometime crewel wool is used to embroider the seams, much like a crazy quilt. If you Google felted sweater quilts you will find some photos and some ideas. Felted wool and felted sweaters are not the same, so keep that in mind when reading about any projects you find. :)