Making a Real Den Den Mushi (One Piece)

A real-life One Piece Den Den Mushi speaker whose mouth moves automatically in sync with any sound it plays.

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Things used in this project

Hardware components

Arduino Nano R3

Story

Making a Real Den Den Mushi (One Piece) — Animatronic Talking Speaker with Arduino

The Den Den Mushi (Transponder Snail) is an iconic communication device from the One Piece universe. In this project, we'll build a real-life Den Den Mushi whose mouth moves automatically along with any audio being played — made from cardboard, servo motors, and an Arduino Nano.

Part 1 — Parts Required

Arduino Nano
9V battery
9V clip connector
Switch
Jumper wires (Female-to-Female, Male-to-Male, Female-to-Male)
Cardboard
Mini breadboard
5–6V battery, 6000mAh
GY-MAX4466 microphone amplifier
2x Servo motor MG995
2x Breadboard (for Arduino)
Modelling clay
Speaker with microphone

Part 2 — Wiring the Components

The wiring for this project follows the requirements of the code below:

Servo 1 → digital pin 9 on the Arduino Nano (lower jaw)
Servo 2 → digital pin 10 on the Arduino Nano (upper jaw)
GY-MAX4466 (mic amplifier) → audio output (OUT) to analog pin A1 on the Arduino Nano
GY-MAX4466 → VCC to Arduino 5V, GND to Arduino GND
Servo motors → powered from the separate 5–6V 6000mAh battery (not directly from the Arduino, since servos draw more current than the Arduino can safely supply), with the servo battery's GND tied to the Arduino's GND (common ground)
9V battery + clip connector + switch → main power source for the Arduino Nano, connected through the switch so it can be turned on/off
All components are assembled on the mini breadboard and the Arduino breadboard to keep the build neat and easy to reassemble.

Part 3 — Cutting the Cardboard to Shape the Den Den Mushi

For the exact cardboard cutting details, check out my YouTube video, since the shapes are easier to understand visually.

Broadly, the steps are:

Cut the cardboard into two half-circle pieces to form the upper and lower jaws of the mouth.
Attach each cardboard piece to a servo motor horn — one servo for the upper jaw, one for the lower jaw. These are the parts that will open and close to mimic a mouth "talking."
Once the cardboard frame is ready, cover the entire outer surface with modelling clay to give it the shape of a Den Den Mushi from the One Piece anime — including sculpting its two characteristic eye stalks.
Inside the cardboard shell, place all the electronic components (Arduino Nano, breadboard, GY-MAX4466, battery) along with the speaker that already has a built-in microphone, so everything stays neatly hidden inside the Den Den Mushi's body, with only the mouth and eyes visible from the outside.

Part 4 — Program the Arduino

Open the Arduino IDE, and make sure the Arduino Nano board and the correct port are selected under the Tools menu.
Install the Servo library if it isn't already installed (it's usually included by default in the Arduino IDE).
Copy the code from Part 2 into a new sketch.
Upload the code to the Arduino Nano.
Open the Serial Monitor (baud rate 9600) to view the amplitude values from the microphone — useful for calibrating the sound threshold (the value 320 in the code) to suit your room's conditions.

How the program works, in short:

The program reads the audio signal from the GY-MAX4466 microphone via pin A1 for 25 milliseconds to get an amplitude value (the difference between the highest and lowest signal readings).
If the amplitude exceeds the threshold (320), that value is mapped (map) to a mouth-opening angle (0–27 degrees).
A "pulse" mechanism makes the mouth open and close repeatedly every 180ms so the motion looks like talking rather than a static open position.
The angle value is smoothed (smoothing) so the servo movement isn't jerky.
Servo 1 (lower jaw) and Servo 2 (upper jaw) move in opposite directions from their base positions (baseLower and baseUpper) to open the mouth.

Part 5 — Testing

Once everything is assembled, it's time to test it.

Play some sound/audio near the microphone on the speaker. The captured sound is read by the GY-MAX4466 module, and if the signal's amplitude crosses the threshold set in the code, the Arduino drives both servo motors so the Den Den Mushi's mouth opens and closes in sync with the sound — just like it's "talking."

With that, this animatronic Den Den Mushi project is ready to be used as a unique speaker whose mouth moves automatically every time sound comes out of it.

Code

Code

#include <Servo.h>

Servo servo1;
Servo servo2;

const int micPin = A1;

int baseLower = 70;
int baseUpper = 90;
int maxOpen = 27;

int openSmooth = 0;

unsigned long lastPulse = 0;
bool forceClose = false;

void setup() {
  Serial.begin(9600);
  servo1.attach(9);
  servo2.attach(10);

  servo1.write(baseLower);
  servo2.write(baseUpper);
}

void loop() {

  int signalMax = 0;
  int signalMin = 1023;

  unsigned long startTime = millis();

  while (millis() - startTime < 25) {
    int sample = analogRead(micPin);

    if (sample > signalMax) signalMax = sample;
    if (sample < signalMin) signalMin = sample;
  }

  int amplitude = signalMax - signalMin;
  Serial.println(amplitude);

  int target = 0;

  if (amplitude > 320) {  
    target = map(amplitude, 320, 900, 0, maxOpen);
    target = constrain(target, 0, maxOpen);
  }

  // ===== PULSE MOUTH =====
  if (millis() - lastPulse > 180) {  
    forceClose = !forceClose;
    lastPulse = millis();
  }

  if (forceClose) {
    target = 0;  // paksa tutup sebentar
  }

  // smoothing
  openSmooth = openSmooth * 0.7 + target * 0.3;

  servo1.write(baseLower - openSmooth);
  servo2.write(baseUpper + openSmooth);

  delay(50);
}

Credits

Barqunics

7 projects • 75 followers

Hello, My name is Ikhsan

Making a Real Den Den Mushi (One Piece)