Billiard balls have been made from many different materials throughout the history of the game , including clay , wood , ivory , plastics ( including celluloid , Bakelite , crystalate , and phenolic resin , polyester and acrylic ) and even steel .
For example , they have been made from clay , wood , ivory , plastics ( including celluloid , Bakelite , crystalate , and phenolic resin ) and even steel .