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

The LEGO Arduino Cookbook Chapter 11: Favorite Color Machine

Chapter 11 of The LEGO Arduino Cookbook builds a machine to contemplate your favorite color, as in the video below. LEGO motors are repurposed in this project to serve as adjustment knobs, with one knob for each of the constituent colors of red, green, and blue.