Here is a DIY project that should prove fun to Star Wars fans. Pardopoz has posted a guide that shows you how to build a motorized Star Wars AT-ST that reacts to sounds. It is built with an Arduino Nano, 3D printed parts, microphones, and a few other parts. You are going to need a AT-ST Walker Star Wars Model from Bandai to get started.
The above video shows how this motorized AT-ST works. As you can see, it detects sound and turns head towards the source. The code and all the instructions are available on Instructables.com.