Hey Bill, great stuff!
I'm planning on making a very similar bag myself, and I was wondering if you wouldn't mind sharing the dimensions of the initial cutout of the shell (as pictured in the first photo)? It would be incredibly helpful as a guideline.
Also, how did you manage to make the sewn edge look so neat? Did you sew it so the edge of the fabric is now on the inside, and if so, does that bother you when you're in the bag?