Method of adapting a relatively small number of bowling balls for testing use by a relatively large number of bowlers

A method for adapting a relatively small number of bowling balls for use in testing by a large number of bowlers having different hand sizes, said method including the steps of:

• predrilling a pair of finger holes of a standard size in each of said relatively small number of bowling balls, which finger holes are shaped to receive removable finger inserts of varying sizes,
• predrilling a thumb hole in each of said relatively small number of bowling balls with said thumb hole in each of said bowling balls being located at a different, predetermined distance from said pair of said finger holes so that each of said plurality of bowling balls has a thumb hole at a different distance from said pair of said finger holes,
• installing a removable insert in each of said thumb holes, and
• sizing one of said removable inserts in each of said thumb holes of said relatively small number of bowling balls to accommodate the thumb of a bowler testing said bowling ball.