Kathleen from Grosgrain and The Tumtum Tree shares a video tutorial showing how to add foldover elastic (FOE) to the edge of a piece of fabric. FOE comes in a wide variety of colors and is an easy to to simultaneously finish the edge and add a bit of stretch. There are some tricks to stitching it down, though. Go to the video to see how to to do it.
[photo from Grosgrain]