Introduction: Halloween Skull

The date matches us to create a project based on halloween. We have designed half of a body skull with 3 different functions. First, it has a distance sensor which controls if someone is near 10 cm. In case the answer is yes, it activates 2 leds that play the role of the eyes. Also, starts to move the jaw up and down as it is speaking. To end, a noise imitating a scream shout comes out from the speaker.

Step 1: Materials and Tools



  • Skull and hands of plastic
  • DM wood (4mm) painted in black
  • Paperboard
  • Wire
  • Thread
  • Cloth


  • Arduino UNO board
  • 2 Red LEDs
  • 2 220 ohms resistor
  • Cables
  • Servo motor
  • Distance sensor HC-SR04
  • Dfplayer Mini
  • Micro SD card
  • A speaker


  • Hot Glue
  • Laser cutter
  • Welder
  • Scissors

Step 2: Electric Scheme

Step 3: Flow Diagram & Code

Step 4: Build the Skull Structure

Create a circle with 2 turns using the wire. Do not cut the wire and follow by extending it up until the structure has 50 cm more or less. Then we need 2 boxes made of paperboard to keep the head straight. For the biggest box’s dimensions, 30 x15 x10 will be enough. We make another box with a paperboard, this time a little bit more tiny to put it above the other box, more or less 10 x 7,5 x 5. The next step is to put the boxes across the wire so we could have a more stable structure. The skull is going to be located above the smallest box. In order to hide all the structure that we have already built, we use some cloth and thread for the head. All this is matched with hot glue.

Step 5: Make Arrangements

To introduce the Arduino UNO into the skull we need to make a hole in the back of the head with the scissors. This way, all the components except the distance sensor and the speaker will be hidden.

Another essential aspect is to create two little holes in each eye so we can insert the red LEDs. To do this, we need a drill that is a bit more tiny than the diameter of the LED.

Also, it is necessary to create a mechanism that lets the jaw move at the same time as the servo motor. To achieve this, the jaw needs to be anchored to the servo motor blades (these ones have to be out of the head and just in the middle of the jaw’s subjection). So, we will need to make a bigger hole to come out the servo motor part. The jaw and the blades are going to be joined with hot glue. In case it is not really stable, it can be used with some zeal.

Step 6: Build the Box for the Sensor and Speaker

The distance sensor HC-SR04 and the speaker must be out of the structure so they can do their function properly. In order to keep the esthetic of the project, we built a wood black box to hide these components. The easy and effective way to do it is with laser cut. The dimensions of the box can be modified but the hole ones no, because these ones will be used to put the sensor and the speaker. Once we have all the boxes sides cut by laser, we will make an assembly with hot glue. So as to make it more of halloween, to decorate the box with spiders and pumpkins.

Step 7: Make All the Necessary Connections and Weld

To start with, once we have all the components located in the right place, it's essential to connect them properly to the arduino base. In our case, some components were too far to reach them with one short cable, so we have to weld in order to maintain a coherence.

Step 8: Conclusions

To conclude, we can say that making an interactive decoration for halloween is not that complicated. It is enough to know some basic notions of computing and electronics to be able to make the circuits in the arduino. The result is very attractive because it plays with the user who is close to the decoration. In addition, the surprise factor of the scare manages to impact the users.

Halloween Contest

Participated in the
Halloween Contest