Using the original bat, trace the outer circumference and the openings for the pins. Work the placement so that you can get as many bats as possible out of the particle board.
Be sure to be as accurate as possible when marking the pin openings. Angle the marker and be certain that it is hitting all the way to the edge. Even a small inaccuracy in the placement will make the bat unusable. (If this does happen, mark and drill a second set of pin holes well away from the first set. Use indelible marker to distinguish the good set from the unusable set.)