For building a [foldable SOF]? boat, many have used Hypalon?® by Dupont®. A much cheaper and useful material is a roofing material such as Elasticote?® or Snowcote?®. These materials, once applied, can be folded and unfolded again without leaking. Some users have complained that the Snowcote® tends to abrade (wear off) easily if scraped over rocks or oyster beds.