This project is a beginner LED POI that can be built for under $25 for a pair (if you scrounge a few parts).
It uses an RGB LED with ping pong ball for diffuser, 9 volt battery, Arduino pro-mini (or nano) and 3-axis accelerometer board. It teaches the basics of connecting things to the Arduino, programming the Arduino, both input from the accelerometer and PWM to control the RGB LED.
