Thanks to Sabine Lintner of Trachtenwerkstatt for showing me this, and for doing the step-by-step instructions for us.
This is a trim, made by constructing and sewing a tube of fabric, and then, pleating it. After the trim is constructed it can be attached to a surface of a garment to embellish it.
1. Cut a length of fabric, twice your desired width plus 2 x your seam allowance.
2. With right sides together, sew the tube lengthwise.
3. Turn and press.
4. Using chalk, mark every 1” on the strip (or other length, depending on how deep you want the pleats.
5. Using an iron, press in the pleats, These are box pleats. See the picture for detail.
6. Carefully lay the folded band onto the sewing machine, and stitch a line down the center and over the folded pleats. This line will secure the pleats in place.
7. Using the illustration as a guide, folder two edges together, and with a needle and use a whip thread stitch to permanently attach them. Continue this along the length of trim.
8. Attach the grim to your garment.
Note: If you like, you can attach the trim to your garment as you stitch the line that holds the pleats together (Step 6).