The cutting and sewing of the side panels of the mantles begins. It is very much like the tailoring of a coat or jacket. My memory of procedures for hems, facings, and linings is a bit rusty, and what should appear out of the blue but Tien's post with a link to a lining tutorial! So helpful, and what incredible timing. I made a small sample, and that mysterious inside corner where facing and hem converge looks perfect.
Now that all the side panels are cut out, it appears that I was overly generous in my estimates. Look at what's left over: