Stick,
Yeah: material, material, insulation. Here's a diagram from when I was planning things (note I changed the drawcord channel, and left out velcro):

I had planned to top-stitch the side seams as well, but it looked just fine without. As I said, I found closing the top (neatly) a little challenging. Next time, I'd leave a smaller unsewn seam, in a less conspicuous spot, and prob. baste the "middle layer of fabric to the insulation before turning right side out.
I enjoy your blog, BTW.

