Buttons are great; they turn things on, call for elevators, and ring doorbells. 3D printed optics will bring a glowing twist to the rewarding press of a button.
Disney has a long term vision of creating interactive devices that are completely 3D printed, and part of that vision is Printed Optics.
Disney is using 3D printing again, in one of their Disney Experiences. In this case, little girls can have their faces placed on a 7″ Disney Princess.