I started out sewing batting together by hand with a whip stitch. (I also overlapped the pieces first and cut them with a wavy line, as instructed in the books.) That was tedious. Then I tried fusing the pieces. That worked okay, but I don't always have fusible available, and it was a pain having to lay the batting out on the ironing board. Now I just sew them together with a zigzag stitch on the sewing machine, and that is easiest and quickest for me. After the quilting is done I can't tell how many pieces of batting are inside, or where they might be joined together. For a comfort quilt I recently used up most of my batting scraps, even some of the smaller pieces. No more wasting batting for me!