So we are starting with the easiest sewing first!!
4. Trim the seam allowance down to about 1/4" and cut the corners off so it will turn nicely.
5. Turn it so the sash is right side out and press.
6. Fold the seam allowance in at the middle and press so you can hand slip stitch the gap you used to turn it.
7. Sash done! (We'll trim it later)