Last night I completed a hammock pod/sock. It's modeled after a bug bivvy I made a while back, (also modeled after Blackbishop's hammock sock, and Just Jeff's hammock sock and Risk's travel pod) and it consists of 2 sheets of 125" x 60" 1.9 oz. DWR ripstop sewn together to form a tube, with a 96'-ish #3 zipper (with 2 reversable pulls that close head-to-head) at one seam and paracord drawstrings at the ends.
It's basic purpose is to keep the warm air surrounding you (created by you) from blowing away in very cold weather, or to keep the wind or moisture from mist or fog at bay. From reading of other's experience with these things, I'm expecting the air inside the pod/sock to remain about 10 degrees warmer than the surrounding air.
The drawstrings at the ends allow for easy setup and ventilation on each end, and the zipper allows the pod/sock to be completely closed on the ends, but still allows flexible ventilation through a moveable, resizable, zippered vent hole (like Risk's pod). You can either pull it up over you like a sock, or leave it set up completely and enter through the side zipper entrance. The zipper entrance can also act as a window to outside, which I find pretty important.
I have no idea what it weighs, but it could (always!) be made to be lighter, by using lighter materials (lighter ripstop, etc), these were just the materials I had at hand. I did use a lighter zipper, #3, and also pulled the center fibers out of the paracord, but the biggest difference would be the weight of the material itself. I also didn't try to taper the material like Risk did.
It was a fun project. I watched a lot of Football and Nascar while making this thing. Too bad my teams all lost.
I'll post some pics this evening, when I get a chance.
Waiting for some time to test it out, maybe next weekend.