I was thinking of making one out of cuben fiber...just for the fun of seeing how light I could go. The fabric weight in my last pack, using 1.9 ounce uncoated nylon, came to about 6 ounces. So, with cuben fiber, I could save about a quarter of a pound (4 ounces) by using cuben fiber. I haven't worked with it before but the experience of others is promising.