Published November 10, 2026 © CC BY

Remy the Rat

Who doesn't want to dress up as Alfredo Linguini for halloween? With a fully functioning Remy the Rat on their head!!

BeginnerFull instructions provided6 hours9

Things used in this project

Hardware components

Espressif ESP32 Development Board - Developer Edition

SG90 Micro-servo motor

4xAA battery holder

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

heat gun + shrink wrap

Story

I am absolutely obsessed with rats and pigeons so every year for halloween I dress up as some sort of rat or pigeon and last year I saw @SheBuildsRobots idea for Remy and I knew I had to try it! This project had a lot of firsts for me:

First time being able to wear something I made
First time having a correct external power supply
First time drawing a schematic circuit diagram (I usually just wing the wiring hahah)
First time 3D printing
First time editing an stl file (unfortunately claude helped) https://github.com/shebuildsrobots/remy_model/pull/14

The microchip I was able to burry in my hair and the battery pack went into the "temperature gauge" pocket of my chef shirt 🤣 🤣 🤣

Showing the back of the rat

Videos:

Things I would do to make it better:

The wires that were connecting the servo motors to the 3D printed arms (some 24 gauge jewelry wire I had laying around) kept breaking or they would bend weirdly and the arm wouldn't move up. So I would want to figure out a different way to do that joint. The motors are too big to fit into his shoulders so maybe I would try to do a tendon joint next time? I have never tried those.

Code

Moving arms up and down randomly

#include <ESP32Servo.h>
Servo rightServo, leftServo;

// credit to @shebuildsrobots for the initial idea and code!

void setup() {
  pinMode(A0, OUTPUT);
  pinMode(A2, OUTPUT);
  leftServo.attach(A0);
  rightServo.attach(A2);
}

void loop() {
  // Adjust the random params within the range for each servo. 
  // We move to a random location near the bottom of the servo's range,
  // wait a random amount of time, the move to a random location near the 
  // top of the servo's range.
  rightServo.write(random(5, 20));
  delay(random(850, 1150));
  leftServo.write(random(5, 20));
  delay(random(850, 1150));
  rightServo.write(random(150, 160));
  delay(random(850, 1150));
  leftServo.write(random(150, 170));
  delay(random(850, 1150));

  // I screwed in the arms of the servos differently and also the servos are
  // rotated I think? so if I set the arms to:
  // left - 0 - vertically up
  // right - 0 verticaly down
  // left - 180 - vertically down
  // right - 180 - vertically up
}