Before sewing the layers together I basted a waist tape to the interior layer.
That is a rather narrow ribbon to be using as a waist tape. I have plenty of wider grosgrain, in a few lovely colors, but the only white ribbon happens to be 1 centimeter wide. It's better than nothing. So, I laid the two layers together face-to-face and stitched together along the center back. After pressing the seam allowances open I flipped the whole thing right side out. Here are the layers mid-flip.
Isn't that gorgeous? Does anyone else see a hint of Georgia O'Keefe in that picture?