To start with, of course, you’ll need the ball. That’s easy enough, using the Oval Tool (with the shift key held down to keep it constrained to a 1:1 proportion) and either a solid fill or a gradient fill, depending on how you want your 8-ball to look. (Hey, what do I know, you may want a hot pink Magic 8-Ball.) For mine I used a predominantly black radial gradient with a sharp falloff to a small white center, then used the Fill Transform Tool to shift the gradient so that the white center could be a highlight for the ball.

