Rouleau straps are used for button loops, ties, spaghetti straps, or embellishments. It is basically a bias-cut tube. A loop turner is a great too for turning these narrow tubes to the right side.
Another option is to fill the tube with piping cord to give it more structure.
1. Cut a bias strip 4cm wide.
2. Fold the strip right sides together and stitch.The distance between the fold and your stitching line will be the width of your strap. 6mm from the edge is a good width for lighter fabrics and 1cm for thicker fabrics.
3. Cut one end at a sharp angle. If you would like your rouleau strap to have some body and hold its circular shape then do not trim the seam allowances. If you are happy for your strap to be flatter and less full then trim your seam allowance down to 2-3 mm.
4. Unlatch your loop turner and insert it in to the strip.
5. Hook the loop tuner over the cut end and poke the latch through the fabric.
6. Close the latch then gently pull the fabric through. Ease it through slowly initially to get things moving.
7. Pull until you have your rouleau strap pulled all the way through until the right side of the fabric is on the outside.