If you want to make your own start out with a strip of fabric 4 times the finished width you want. Fold srrip in 1/2 lengthwise & press. Open the strip out & fold each side to the folded center line & press. Fold & press again along your original center line then top stitch close to the edges. This will give you a nice finished edge. You could also sew a tube & turn with a safety pin then press. Just make sure your tube is wide enough to fit the pin through.