The resulting chair is really comfortable. It feels like sitting on rubber bands. The trick is to have narrow enough spacing and a tight-enough weave so that your weight is evenly distributing across as many lengths of hose as possible, which will in turn evenly distribute the stress on the hose, preventing sagging and long-term decay.
The overall form is quite reclined, with an interior width of about 22". Assuming the hose is recycled (garden hose would work as well, though it typically is made from thinner rubber), the only other materials are one 2'x 2' piece of 3/4" plywood and four 2' x 1/2" dia. threaded rods with nuts and washers. There is almost no waste from the process, making it quite efficient for both the environment and your wallet. Out-of-pocket costs are about fifteen-twenty bucks, depending.