Batting
Years ago I picked up some very good advice for butting batting (interesting word play). The person suggested overlaying two pieces of batting and then using your rotary cutter, cut a serpentine line down the two pieces of batting. At that point, take it to your machine and stitch it together using a zig-zag stitch. Cutting it like this makes the two pieces fit together nicely. I find that this method makes the pieces lay smoothly and fit together very well -- no lumping or stretching.