I want to make a bivy sack that doesn’t need to be totally waterproof, just generally windproof/dew/frostproof. The most important thing is that it’s breathable, so my down bag doesn’t get soaked with condensation, and lightweight/less than a pound (for stuff like winter camping in a megamid, or summer backpacking under the stars when it’s breezy). Epic fabric by Nextec seems like a good option - black diamond makes a winter bivy entirely out of epic that weighs under 10oz - but what else? Anybody have any ideas or suggestions? Cheaper material? Bad/good experiences? I’d like to find a fabric that I don’t have to line, just ready to wear, and it wouldn’t have contact with the ground, just my sleeping pad. I’ve never made anything like this before! Any informed thoughts or suggestions would be appreciated!