Slide of Tooth Decay
About
For Halloween, Dave Johnson and I decided to built an electromechanical candy slide that distributes Skittles and M&Ms when trick-or-treaters hit a big game show button. We ended up with a fog machine, lots of lights, and a lot of smiles.
Construction
We started out with an eight-foot length of 3" PVC pipe to act as the slide. Our friend Mike Bowden was kind of enough to cut it lengthwise into two pieces and allow us the use of his woodworking shop to smooth the edges. His lathe burnished the inside of each piece to a flawless smoothness and carnuba-waxed shine.
While the glue was drying on the slide, we had to figure out how to dispense the candy. We decided to use vending machine coils turned by DC motors activated by the game show buttons. But the motors and coils still needed a fixture in which to turn, so we went back to PVC and built a frame to hold both of them.
With a place to put the motors and coils, it was time to rig some wires and write some Android code. When a button was pushed, the corresponding motor was meant to turn the coil one revolution in order to release candy down the slide, and gravity would do the rest.
On Halloween day, we temporarily assembled all the pieces and tested it out with actual candy. For such a shallow slope from the kitchen counter to the floor, it actually worked pretty well.
Now it was time to put up a 6-foot tall shelving unit to serve as the "tower" for the slide. The shelves worked great as a place to hold the motor tray, fog machine, and power bar, and the unit's frame served well as an anchor point for zip ties holding everything in place. A white sheet finished it off to hide all the mess and control the fog output and placement.
Finally we added colored strip and rope lights and attached the light-up buttons to the Arduino with speaker wire. A webcam at the top of the slide showed the vending mechanism in real-time, and we finished off the look with our favorite skeleton friend for increased spookiness.
The trick-or-treaters loved it! We told kids it was a game where they could race their friends for candy and gave them a countdown. Whomever hit their button first and got their candy to the bottom of the slide soonest would win! And no one knew which button corresponded to which slide, so everybody went home with candy. We had some groups return later just to play again, and plenty of kids who kept hitting the button just to see the candy go down the slide.
It was a great low-budget project and we're planning to build a Version 2 for next Halloween with improved candy propulsion, delivery efficiency, and perhaps sound effects. We learned quite a few lessons and solved unforseen problems with on-the-spot innovation. And we got to deliver candy with a big, chaotic ruckus that the neighborhood will remember next year.
