My daughter really wanted to be a stoplight for Halloween, so my wife asked me if I could get it to light up. We came up with a stoplight that had a "normal" mode where the lights would change from green to yellow to red, and also had a "dance party mode" where it played the Halloween song from the Nightmare Before Christmas and Michael Jackson's Thriller while flashing the lights in different sequences. There was a button on the side for my daughter to control what mode it was in. My youngest daughter is too young to decide what she wants to be so we made her the pedestrian sign. Both costumes are based on Arduinos.

Step 1: Parts

The stoplight costume had the following parts
-Cardboard box with holes for the head and arms
-Arduino
-Ladyada Wave Sheild
-6 - 74HC595 shift registers
-speaker
-Battery Holder and 4 AA batteries
-48 LEDs (we did 12 red, 12 yellow, 12 green, and we had 12 reserved for other lights around the costume)
-48 resistors

The Pedestrian sign used the following parts
-Arduino
-6 - 74HC595 shift registers
-48 LEDs (24 red, 24 white)
-48 Resistors
-Battery Holder and 4 AA batteries
-Piezo buzzer

Step 2: Stoplight Assembly

Build the Wave Shield ( www.ladyada.net/make/waveshield/ ) and connect to the Arudino. To connect the shift registers follow the tutorial on www.arduino.cc/en/Tutorial/ShiftOut . The only difference is when you connect the shift registers to the Arudino you need to use pin 9 for the clock pin and pin 6 for the data pin because the Wave Shield uses some of the pins the Shift out tutorial also uses. Connect a button to analog pin 1 for setting the stoplight to normal mode, and analog pin 2 to start playing a song. The first time it will play the song from Nightmare Before Christmas, the second time it's pressed it will play Thriller. The buttons are connected to ground (the buttons I used are "normally closed momentary buttons".