This device created by student designers Yingjie Bei and Yifan Hu only looks like an artsy turntable, but it can't play your vinyl collection. Here's what it can do, though: show you the right moon phase for any particular day. When you input the date you want through its three knobs, the Arduino board inside it uses a programming language called Processing to do computations and identify the correct phase. After that's done, the Arduino moves the device's motors, which in turn move the flashlight. It then shines light upon a miniature cement moon, which shows the phase for the day from the operator's POV. If you think it sounds like a fun little project for your home planetarium, check out Bei's website, where you can see early sketches and in-progress pictures for more info.
[Image credit: Brady Bel]