Sports products are highly regulated and golf balls are no exception. However, the dimpled cover for a golf ball is unrestricted in terms of the shape, size, depth and quantity of dimples per ball. Golf ball covers are usually injection moulded using thermoplastic materials; eg DuPont's Surlyn. If it were possible to 3D Print a golf ball cover over a synthetic rubber core using an appropriate thermoplastic. It would open the door for every golfer to design and manufacture their own golf balls. As golf balls have a relatively small diameter and cover thickness minimal, the amount of material used and hence cost should be reasonable.
Please get in touch if you think you can 3D Print a golf ball cover in a single piece over a synthetic rubber core. You might just start a revolution.