I found this online and are building 10 of them. They are made from plastic barrels cut in half. I also cut out most of the ends so that fish could swim underneath as well. Each one has 20 five foot pieces of 1/2" irrigation tubing looped through the holes I drilled. Total cost: Barrels were free and tubing costs $35.98 per 500' roll. I used two rolls so I have less than $80 in the entire project.