Many years ago I found this small slide light box in the trash, the fluorescent bulb inside was dead, and it was designed to run on huge D cell batteries. A bit impractical and expensive to use, and too cumbersome to find a matching fluorescent bulb to replace the old one with.
I had a bunch of slides that I needed to archive, so it would be nice with a tool like this to inspect them. I decided to hack and modernize it a bit.
I found a big Perfboard, and soldered on some 5050 SMD LEDs that I had salvaged from a broken lightbulb. I cut out the old battery holder with a Dremel to make space for the new electronics. To keep it portable, I added a 18650 Lipo battery cell and a charging circuit. To make it simple, I used a circuit board meant to drive a LED flashlight to control the voltage and current to the LEDs. This meant that the light box got some extra light modes. I can even dim the LEDs a bit.
It ended up looking like nothing had been changed, which for me sometimes is a good benchmark, and I really like the style of it. Now it can even be charged via USB.