I'm a bit new to backpacking, but I've been looking around at gear and I see that lightweight backpacking these days is a pretty big deal. I've got recurring back problems, so I want to lighten my load as much as possible.

I'm really interested in the Grand Trunk hybrid hammock/shelter, but I don't like the price tag so much. Why pay 80 bucks for a sheet of waterproof nylon when I have years of sewing experience? It looks pretty easy to make, I just don't know what kind of material I should make it from. Is it okay to make a waterproof hammock out of coated nylon, or does the hammock have to breath for some reason? What is the right weight of fabric that I should use so that it's strong enough to hold me? I'm 5'6", 170 lbs.