Polyethylene terephthalate forms the basis for synthetic fibers like Dacron, Terylene and polyester. Modern lines are made from artificial substances, including nylon, polyethylene, dacron and dyneema. The aircraft is made from composites, with its double surface wing covered in Dacron sailcloth. These slips were made of 50% nylon and 50% dacron polyester. Fly line backing is usually composed of braided dacron or gelspun monofilaments. It is usually a flat woven webbing made of nylon, cotton, or Dacron. Bowfishing line is often made from braided nylon, Dacron, or Spectra. Manufacturers also experimented with rayon and newer fabrics like Dacron, nylon, and Spandex. Originally, the sloop designed Phantoms were built from plywood with metal masts and Dacron sails. Some materials used for the inner covers are Dacron and Nomex Netting. A smaller, 3.8 m sail made only of Dacron (polyester) is also available. The Weedhopper is constructed from aluminium tubing and covered with Dacron pre-sewn envelopes. The catamarans had modern Dacron sails, Terylene stays and sheets with modern roller blocks. The wing is an aluminium frame covered with pre-sewn Dacron envelopes. She also imported the synthetic fabric Dacron.