What Ken said, play around with it, the least amount of foam will be better, the water on the fabric bottom provides plenty of cushion.

At some point when I have more time I want to play around with the idea of a fabric sling seat, I just haven't had the time. Really a minimal seat, a few ounces of fabric and a couple bent aluminum tubes being the whole seat, should weigh nearly nothing and from past experiences should be quite comfortable if designed correctly.

Bill H.