Two options I can think of.
Option #1: Buy white thigh highs and sew the additional decorative section to the top. You will attach the pieces along the bottom red ribbon, so the piece looks like it's part of the thigh highs.
Option #2: Create Duct tape leg dummies. There is a tutorial floating around the Internet somewhere. Then, you can do the method she does in the tutorial. Stretch the fabric over the "leg", pin, carefully remove, and sew along the pins, thus creating the seam. The upper part will be tricky, but you can cut the shape, then edge the fabric with red bias tape or ribbon.
Don't know if I've explained these methods very well. The first option may not be as accurate, but it will be easier. I believe Lady Ava did this method, and it looks fine. Good luck!