Callahan first began flint knapping in 1956. The Levallois technique for knapping flint developed during this time. This allowed for more forgiving flint knapping. They created stone tools made out of chert by chipping, knapping and flaking. Early European explorers to the New world were also exposed to flint knapping techniques. These authors helped to ignite a small craze in knapping among archaeologists and prehistorians. More sophisticated knapping is employed to produce near-perfect cubes which are used as bricks. This process is referred to as knapping. Knapping is often learned by outdoorsmen. Knapping was done using antler batons, hardwood batons and soft stone hammers.