Four miniature LEGO 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.
I’ve received some negative feedback over the pitch of the music in the sound effects, but I went on to sell each and every one of these models at A Video Game Con in fall 2015.
See the tutorial on Instructables