I had seen a picture of a "monster pouch", but there were no details about how it was made, so I had to wing it. The front with the zipper was easy enough - I just stitched front and lining pieces to either side of the zipper, and top-stitched close to the zipper. The challenge was working out how to attach the back pieces. After a few attempts where the seam ripper also got plenty of use, I ended up stitching the outer backing piece to the outer front pieces from the zipper, down the side, along the bottom and up to the zipper. I did the same on the top piece and then on the lining pieces, leaving an opening for turning the pouch inside out. This meant a bit of handstitching along the sides where the zipper is, both inside and out. There might be an easier way of constructing it, but this was what my tired mind came up with last night, and at least it worked.