|I usually use 1/4-inch for diapers. As for the zig zag staying within the borders of the elastic, I wouldn't worry too much about it. When I do it, sometimes the zig zag goes over both edges. Sometimes it's more to one side, sometimes more to the other side, but it always seems to work fine if you are catching at least 50% of the elastic under the stitch. It may not look wonderful, but it works fine.
Thanks, I tried this and it worked beautifully! Finally, my elastic looks good.
Kari Mom, I don't quite understand what you did. It's a 1-layer cover, right? So you made a seam allowance all around, or only at the parts that required elastic? I'm not sure how you got the nice, finished edge all the way around. It looks beautiful!