Yeah, I play with custom balls myself. I don't like playing with balls that are completely spherical, so I spec my balls to be slightly egg-shaped such that they wobble to the right to compensate for my crooked stroke.
Seriously though, what exactly do you mean by "custom balls"? I admit I don't know a lot about equipment, so I'm assuming you just mean that you customized the outward appearance (paint) of the balls, but the weight, size, and material are standard. Is there a standard/specification for weight, size, material for pool balls?...or do they allow for slightly different specs like golf balls?
jsp <~~~ knows nothing about equipment