Main article: Electronic Super Mario Power-Ups

Four miniature replicas of the iconic invincibility stars from the Super Mario Bros. franchise, wired with a custom microcontroller circuit to make the eyes blink and to play audio clips. I’ve programmed the chips with an Arduino Uno; the microcontroller is an ATtiny85, which has music generated by the Arduino melody library. Three of the four stars play the invincibility theme for a few seconds, whilst the fourth model (Rainbow) plays the “Coin Heaven” music from Super Mario Bros. 3, and has blinking color-changing eyes. Each unit is powered by two 3V CR2032 coin cells.

See the tutorial on Instructables