Lego Sherlock Holmes figure focuses a light beam on a Lego criminal with a small magnifying glass.

High-Tech LEGO Chapter 9: Hacking LEGO Light Bricks

Chapter 9 offers a guide to modifying LEGO Light Bricks to create any desired color. A couple of video examples are below.

LEDs are available that change through colors, such as this example that cycles through red, green, and blue.

One project described is to install a UV LED in a Light Brick to build a tool for testing for fluorescence. This video shows a UV Light Brick passed over a $50 bill to see the fluorescent strip embedded in the paper.