If you’re interested in creating your own black-light instrument, the solution is literally in the palm of your hand. Here’s what you’ll need: your smartphone, two sharpies (one blue, one purple) and some scotch tape. Start by taking the tape and folding it on the ends. This way it’s going to pull easily. Then put some tape over the flash on your phone. Take the blue sharpie and color over the tape. Repeat this step again. After it dries put another layer of tape over it, but color this one purple. That’s it! Now you can go hunting for germs. Fun.

https://youtu.be/UITRcw9t4zE