I've drilled and tapped a pool ball for use as a gear shift knob in my 46 Ford 1/2 ton. Hit it with a punch to get the hole started, and then used several drills to get the hole up to tap size. To hold the ball while drilling I used a a pair of 1 x 4's with a hole 3/4 the size of the pool ball, used a hole saw for that, clamped in a vise on the drill press, go slow while tapping.