Hey Leftie, I purchased a pack of several puck lights that push on and off and use AA batteries. I have one under my desk in the office for those times I have to crawl under and mess with wires. They're about 3" round and you can push the center to turn on or off.
These aren't the ones I have, but are very similar...
https://www.amazon.com/HOLKPOILOT-Op...2s9dHJ1ZQ&th=1