I want to put LEDs in a shadow box

First of all I hope I am posting this in the appropriate subreddit. So what I am trying to do is somehow install LEDs into a top of a shadow box to light it up and have it be powered by a battery rather than being plugged into an outlet. Also I want to somehow connect it to a switch so it's not on all the time. Does anyone know of any good tutorials to look at or kits or something to buy? Thank you