LED Stoplight Costume

Re-purpose a boring cardboard box into a Halloween costume that will let you exercise your lifelong goals of traffic control! (And win every game of Red Light Green Light)

For my simple stoplight costume I used the following materials:

-cardboard laptop shipping box

-extra-bright LEDs (20 each red, green, and yellow)

-2-AA battery pack

-wire (I used 22 gauge, with red and black insulation to keep track of power and ground)

-slider switch (4-way if you can find it, to give states for red, yellow, green, and off)

Helpful Construction Tools:

-scissors or X-acto knife

-colored pencils (red, green,and yellow)

-soldering iron

-electrical tape

I first cut a large rectangular section out of the cardboard box and used thinner cardboard that was easier to punch holes through for the circles of LEDs. I measured out evenly sized and spaced circles and filled them in with colored pencil to work on the effect of the costume indoors or with the LEDs powered off. I then measured three smaller concentric circles in each (using various yogurt and peanut butter container lids I had around) to arrange the twenty LEDs of each color evenly within each colored circle. I used a screwdriver to punch small holes for the rounded heads of each LED to show through the cardboard, and pushed them through from behind leaving the leads accessible to solder.

I then connected each LED's positive lead to a resistor and then to a power line per color (as shown in the schematic), and soldered the negative leads for all LEDs to a shared ground attached to the negative side of the battery pack. The power lines for each color went to the three output states of the switch (this will vary based on the switch you get) so that only one color at a time receives power from the batteries. Use plenty of electrical tape to insulate joints and prevent shorts as there will be lots of wires going every which way inside the box, and you don't want to have to open it mid-Halloween-party to fix a problem. This soldering job can be tedious and frustrating because there are a lot of wires and it's hard to efficiently route them around such a wide area. I suggest friends, rocking out to music, and cookie breaks to mitigate this task.

I cut another small hole in the side of the box to attach the switch so that it could be wired on the inside of the box and accessible from the outside. Also, because I was only able to find a 3-way switch and thus had to disconnect the batteries in order to turn the costume off entirely, I cut an extra hole to leave the battery pack accessible from the side.

Finally, I tested out my work, fixed up a couple of loose solder joints, punched a couple more holes to attach a shoelace-neckstrap, then sealed back up the box and got out there to annoyingly direct the walking traffic of my friends all evening.