This is the batting corner corner for my guild's Project Linus stash. You can see we have two huge rolls of batting (one in front, one still in plastic in the back), generously donated by the company that produced it. Unfortunately, it's only 36" wide! I think I've complained about this before.
Several people have suggested ways to piece batting, and now that I have a quilting table, I thought I'd give one of them a try. We have a worknight tonight and I wanted to know before then whether the method I chose would work. It did!
I took two pieces of batting and laid the edges so they butted together perfectly. These were clean cut edges from the manufacturer, but I'm told that with scraps you might want to overlap edges and cut them with a wavy line so they mesh perfectly. I ironed on a tiny strip of fusible web to join the two pieces (you can see the paper still on the fusing in the above photo), then stitched them together with the biggest zig zag possible on my machine. It took just a few seconds to do the whole seam and it lies perfectly flat! Sorry, couldn't get any photos that showed the stitches. But if you want to try joining batting pieces, this seems to work well. If the straight seam becomes a problem, I'll try a wavy edge next time.