Grand Trunk hybrid shelter clone

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.

Think of lying on top of a sheet of plastic that wraps up the sides of your body. That is how a waterproof nylon hammock is likely to feel. You can get more advice than you can absorb if you read up on information at hammockforums.net.
I have a homemade hammock, but keep going back to my Hennessy Hammock. They usually have a “scratch-and-dent-sale” around October, a new hammock sale for Christmas, and used hammocks pop up from time-to-time. (www.Hennessyhamock.com)

Campermom is right about sleeping in a waterproof hammock. There are other concerns.

First, it is designed to be a lot of things. But it cannot do all of them well. After a few nights as a hammock it will be pulled out of plane and will not set up adequately as a shelter. It has no bug net. When used as a hammock it has no rain, dew, frost protection.

Second, you say you are new to backpacking. There is a learning curve. It is safer and more enjoyable if you start with less challenging gear. It you are sure you want to hammock, prudence would advise you to get a turn-key design. There are many. Hennessey is a good idea if you can pick one up at REIs outlet as Campermom said. Hammock Forums has lots of info.

Yes, you want it to breath. Imagine sleeping in foil.

There is a technique to making a hammock. Regular gathered end hammocks are difficult for the novice to hang properly to get a flat lay. Recommend buying a style that jas a ridgeline, is shaped to make it easy to lay on a diagonal, and has some strap/whoopie sling suspension. Nuances matter.