I found an addressable LED strip at Goodwill - cost me about a quarter. I figured how to program it with an Arduino, but then struggled to figure out what to do with it. At another trip to the Goodwill, I found a black plastic tube. That one cost me less than a dime. And with those two pieces in hand, I had the inspiration for a box made of frosted acrylic with a central black chamber for keeping valuables. To make things a bit more reflective, I sanded the box edges smooth and etched a pattern in the sides.
There are four control switches:
A long slider to control brightness
A push button to switch between rainbow and chaser modes
A radial potentiometer to change the speed of the effects