Chocolate Slot Machine by Ricky, Victor, Leland, and Blake

For our engineering class, we had to make gumball machines for a project. We decided to celebrate Halloween this year by making these for the truck or treat at our school. After tossing around several ideas we settled on building a jack-o-lantern slot machine that dispenses 1-inch chocolate coins instead, since it was Halloween at the time. That’s how the Jack-O-Slot was born: part jack-o-lantern, part jackpot machine.

To build the Jack-O-Slot, we used pieces of wood that we glued together to form the body, then painted it orange with black jack-o-lantern features. We added a Raspberry Pi to run the screen in the front window. For candy, we used 1-inch chocolate coins because they fit the dispenser the best and don’t jam. We also made a wooden lever, a chute for the candy to roll through, and a dispenser piece that drops one coin at a time. For electronics, we used the Raspberry Pi, wires, and basic parts to make the screen work. Our tools included paintbrushes, a ruler, scissors, and wood glue/hot glue gun.

The first part of the project was figuring out how to dispense chocolate coins. The first prototype was built from cardboard. It showed the basic concept. Before we started building anything, we planned out how the Jack-O-Slot would look and work. First, we sketched a jack-o’-lantern shape and decided where the lever, the candy chute, and the screen would go. We used OnShape to make a 3D model so we could see the whole machine before cutting any wood. This helped us figure out the size, how the inside would fit together, and where the 1-inch coins would drop. We also planned the front window screen, which would run on a Raspberry Pi to display the slot-machine images. Once the design looked good, we were ready to start building the wooden frame.

To build the main body of the Jack-O-Slot, we laser-cut our wood pieces using Lightburn and then glued them together to create a strong box. This box holds all the mechanics, so it needed to be sturdy and not easy to tip over. We glued the front, back, sides, top, and bottom panels and used clamps to keep everything tight while drying. We also cut out the front window area for the Raspberry Pi screen and a slot at the bottom where the candy would drop. Once everything was dry, we checked to make sure the frame was solid and ready for the internal parts.

Before adding any electronics, we spray-painted the entire wooden frame to give it a clean, smooth jack-o-lantern look. We took the box outside, placed it on cardboard, and used orange spray paint to cover all sides evenly. We did light coats so the paint didn’t drip and waited a few minutes between layers until the color looked solid. Painting early made everything look cleaner, and it was easier to reach every part before the inside pieces were fully installed. Spray painting made the surface look smooth and professional. Once everything was dry, the frame looked like a real pumpkin and was ready for electronics and final assembly.

Next, we added the moving parts that make the Jack-O-Slot work. We started by attaching the lever to the side of the box using a wood dowel so it could smoothly move up and down. Inside the box, we connected the lever to a simple switch and servo system that pushes a release gate for the candy. When the lever is pulled, the switch makes the servo motor turn and lets one chocolate coin drop through the chute. We tested the motion several times to make sure the lever wasn’t too stiff and that the coin always dropped correctly. Once it moved smoothly, we glued the pieces in place so nothing would shift around.

Next, we built the part of the machine that actually gives out the chocolate coins. We made a small chute inside the box that guides one coin at a time from the storage area to the bottom opening. Instead of a simple gate, we used a servo motor connected to the lever. When the lever is pulled, the servo moves the gate to release one coin down the chute. We tested it many times to make sure the coin always dropped smoothly and didn’t get stuck. Once it worked, we secured the servo and gate in place and made sure the bottom slot lined up with the candy tray so players could easily grab the coin.

The slot machine is powered by an Arduino and Raspberry Pi. To make the slot machine images appear on the front, we installed a Raspberry Pi behind the window we cut earlier. First, we mounted a small screen inside the box so it wouldn’t move around. Then we connected the screen to the Raspberry Pi and placed the Pi on a small wood shelf inside the frame. We loaded our simple slot-machine animation using Tinkercad code and tested it to make sure the images spun when the machine turned on. Once everything worked, we organized the wires so they stayed neat and didn’t block the candy chute. Now the screen brought the Jack-O-Slot to life by showing the spinning symbols.

Finally, we put everything together and tested the Jack-O-Slot. We checked that the wooden frame was sturdy, the lever moved easily, the servo released coins correctly, and the Raspberry Pi screen showed the spinning images. We also made sure the wires were neat and nothing inside could jam. After testing and adjusting small problems, the machine was ready. Now, when someone pulls the lever, the images spin on the screen, and if they match, the servo drops a chocolate coin just like a real Halloween jackpot!

Watch the video below to see how it works: