Within league standards there is ample latitude for individual variation, many batters settling on their own bat profile, or one used by a successful batter. Formerly, bats were hand-turned from a template with precise calibration points; today they are machine-turned to a fixed metal template. Historically significant templates may be kept in a bat manufacturers' vault; for example, Babe Ruth's template, which became popular among major-league players, is R43 in the Louisville Slugger archives.
Many players "bone" their bats, meaning that before games, they rub their bats repeatedly with a hard object, believing this closes the pores on the wood and hardens the bat. Animal bones are a popular boning material, but rolling pins, soda bottles and the edge of a porcelain sink have also been used. Pete Rose had his own way of hardening his bats: he soaked them in a tub of motor oil in his basement then hung them up to dry.
The bat's form has become more refined over time. In the mid-19th century, baseball batters were known to shape or whittle their own bats by hand. This allowed there to be a wide variety in shape, size, and weight. For example, there were flat bats, round bats, short bats, and fat bats. Earlier bats were known to be much heavier and larger than today's regulated ones. During the 19th century, many shapes were experimented with, as well as handle designs. Today, bats are much more uniform in design.
Baseball bats are made of either wood, or a metal alloy (typically aluminum). Most wooden bats are made from ash. Other woods include maple, hickory, and bamboo. Hickory has fallen into disfavor over its greater weight, which slows down bat speed, while maple bats gained popularity following the introduction of the first major league sanctioned model in 1997. The first player to use one was Joe Carter of the Toronto Blue Jays. Barry Bonds used maple bats the seasons he broke baseball's single-season home run record in 2001, and the career home run record in 2007. In 2010, the increased tendency of maple bats to shatter has caused Major League Baseball to examine their use, banning some models in minor league play.
Even in those formative years, authorities on the game warned the practice of hitting fungoes should be limited to coaches. Henry Chadwick, one of baseball’s earliest proponents, claimed “The weakest batting is shown when the batsmen indulges in fungo hitting,” according to the Art of Batting. Others agreed that the practice was bad for training a batter’s reflexes: “While watching some of our freshmen practicing ‘fungo’ batting the other afternoon it occurred to me that it was about the worst kind of practice a batsman could imagine in training his eye in batting,” a writer claimed in the March 3, 1886 edition of The Sporting Life. “It trains the eye to meet the ball in batting it in a manner which never occurs in actual play. It ought to be prohibited on every well regulated ball field.”