company, founded in 1948, produced the Wham-O slingshot. It was made of ash wood and used flat rubber bands. The Wham-O was suitable for hunting, with a draw weight of up to , and was available with an arrow rest. The National Slingshot Association was founded in the 1940s, headquartered in San Marino, California. It organised slingshot clubs and competitions nationwide. Despite the slingshot's reputation as a tool of juvenile delinquents, the NSA reported that 80% of slingshot sales were to men over 30 years old, many of them professionals. John Milligan, a part-time manufacturer of the aluminium-framed John Milligan Special, a hunting slingshot, reported that about a third of his customers were physicians. The middle 1950s saw two major innovations in slingshot manufacture, typified by the Wrist-Rocket which was produced by the Saunders Archery Co. of Columbus, Nebraska. The Wrist-Rocket was made from bent aluminum alloy rods that formed not only the handle and fork, but also a brace that extended backwards over the wrist, and provided support on the forearm to counter the torque of the bands. The Wrist-Rocket also used surgical rubber tubing rather than flat bands, attached to the backwards-facing fork ends by sliding the tubing ends over the tips of the forks, where it was held by friction or adhered with the addition of liquid rosin. The early production of the Wrist-Rocket slingshot was a joint effort between Saunders Archery Co., who came up with the trademark and developed the automated forming machinery, and Mark Ellenburg who came up with the basic design. A few years later Mark Ellenburg split away forming his own company called Tru-mark Manufacturing Company. Today Saunders Archery is still a major innovator in the slingshot industry with its line of flatband slingshots which use locking clips for band attachment and tuning. Slingshots are also occasionally used in angling to disperse bait over an area of water, so that fish may be attracted. A home-made derivative of a slingshot also exists, consisting of a rubber balloon cut in half and tied to a tubular object such as the neck of a plastic bottle, or a small pipe. The projectile is inserted through the tube and into the cut balloon, and the user stretches the balloon to launch the projectile. These so-called "balloon guns" are sometimes made as a substitute to ordinary slingshot, and are often used to create the "shotgun" effect