Last week I made a double layer hammock by simply double stitching two pieces of fabric together like I was making a giant stuff sack. I sewed across the bottom then went about 6" up the right side and left a 30" "pull string hole" (if you will) to insert a pad, then sewed the rest of the way to the top. On the left side I sewed from the bottom up and put my 30" pull string hole near the top (basically diagonally from the other one then sewed the final 6". Then I turned the whole thing inside out, and put a rolled hem across the top.
I found this to be a lot easier than hemming 4 sides of two pieces of fabric then sewing the two pieces together, which is how I made my first hammock. So far its lasted a 3 night hang, but I haven't really inspected it to see how its doing. I have to believe there's not much stress on the seams anyway?
If I make another I would make the openings on the side larger, but other than that I'm pretty happy with it.