Hi there. Well, the light is actually what we call an LED tape light, also strip light. It's a low volt light that requires only a small low power wire. The cabinet maker built the shelf with a recess and he wiring was done during construction. The tape light is simply attached (glued, not quite sure??) into the recess. It was convenient of course to provide the power early on, but this is definitely something that can also be retrofitted. So search out led tape lights or strip lights....the cheaper ones will have lighting that is more "stuttered"...a better led light will have a more linear consistent light. Creating a recess in the shelf is easy with a router, or you can hide tape light with a piece or trim......but bringing an obscured power source will be the challenge. Hope that helps and Good luck!!

We just recently did this LED light strip in our kitchen, on top of the kitchen sink, just under the cabinets.
It's great and we can also control the intensity of the light through the switch.
PS - lovely scotch collection :-)