As the picture shown that the right white gear was made only by one mold. This is a kind of  industrial gear. The left two gears are a pair while the left one is of female type and the middle one is of male type. The inner part of the male-type worm gear was joined to a metal cylinder  in order to allow severe wearing within. You may consider how tight the tolerance may need! These are just briefly show you our ability.  Please contact us at: sales-md@hexagold.com