Step 1: List of Parts
Product Link
Step 2: 3D Print Settings
Step 3: Foot Servos Assembly
Step 4: Fix Servos to Body
Step 5: Fix Legs to Body
Step 6: Fix Foot to Legs
Step 7: Head Assembly
Step 8: Electric Connection (Wiring
Step 9: Snap the Head and Upload the Code

Published November 24, 2025 © Apache-2.0

Otto DIY — Build Your Own Robot in One Hour!

Otto is an interactive robot that anyone can make!, Otto walks, dances, makes sounds and avoids obstacles.

BeginnerFull instructions provided1 hour108

Otto DIY — Build Your Own Robot in One Hour!

Things used in this project

Hardware components

Nano ATmega328

Story

Otto is an interactive robot that anyone can make!, Otto walks, dances, makes sounds and avoids obstacles.

Otto is completely open source, Arduino compatible, 3D printable, and with a social impact mission to create an inclusive environment for all kids.

Otto was inspired by another robot instructable Bob-Bipped and programmed using code from another open source biped robot called Zowi.

Otto's differences are in the assembled size (12cm x 7cm x12cm), cleaner integration of components and expressions. Using off the shelf and 3D printed parts, simple electronics connections (almost no welding required), and basic coding skills, you will be able to build your own cute Otto friend in as little as one hour!

This instructable focuses on how to build the basic Otto DIY version, check the other similar robots in our website -https://www.webotricks.com/ and welcome to participate in our different different robotic events.

Step 1: List of Parts

Gather all the off the shelf parts that you'll need for this assembly. Here's the list:

1. Nano ATmega328

Product Link: https://www.webotricks.com/product/arduino-nano-board-soldered-aQt1nX

2. Nano Shield I/O

Product Link: Nano Expansion Shield

3. Mini USB cable.

Product Link:

4. Ultrasonic sensor HC-SR04

Product Link: https://www.webotricks.com/product/hcsr04-ultrasonic-sensor-vFB5iW

5. Mini servo SG90 9g x4 (each one should come with 2 M2 pointed screws and one small screw).

Product Link: https://www.webotricks.com/product/sg90-or-mg90-servo-motors-180-degree-rotation-d1n6DL

6. 5V Buzzer

Product Link: https://www.webotricks.com/product/small-piezoelectric-buzzer-5v-passive-buzzer-3xJzPv

7. Dupont F/F cable connectors 10cm x6.

Product Link: https://www.webotricks.com/product/jumper-wires-20cm-10-pieces-pack-RhmyKI

8. 4 AA Battery case stacked with switch soldered

Product Link: https://www.webotricks.com/product/4xaa-battery-holder-black-gSl1PB

9. AA alkaline batteries x4. 1.5V each

Product Link:

10. Mini cross screwdriver.

it is important to be magnetized you will se why ;)

And then you only need to 3D print 6 parts in total:

Product Link:

11. 3D printed head.

12. 3D printed body.

13. 3D printed leg x2.

14. 3D printed foot x2.

Product Link:

Optional: cutter for post cleaning the 3D parts (if the 3D print quality is good enough no need) and a soldering iron (if you want it battery power otherwise you can still connect it through USB to energize)

That's all simple!; If you do not have a 3D printer you can always use services or local maker spaces.

Step 2: 3D Print Settings

Otto is very well designed for 3D printing, the files that you had downloaded are property oriented and centered, so wont give you trouble if you follow this common parameters:

Recommended to use a FDM 3D printer with PLA material.
No need supports or rafts at all.
Resolution: 0.28mm
Fill density 15%

For slicing and generating the g code for the machine freeslicer software like Prusa Slicer(If you are outsourcing the printing no need to worry about it)

After printing you will need to clean a little bit the legs and feet areas that fix the motors.

Step 3: Foot Servos Assembly

Put the micro servo inside feet and then push it inside, if is to hard maybe need to clean more the area with a cutter.

Is very important to check that the servo is able to rotate at least 90 degrees to each side.

After checking the movement use only the small screw to fix it.

Same process for the other foot.

Step 4: Fix Servos to Body

Take the other 2 micro servos put them in the defined locations in the 3D printed body and fix them only with the pointed screws.

Step 5: Fix Legs to Body

Connect the legs to the hub of the micro servo, important like the foot servos you must check the legs are able to rotate 90 degrees each side respect to the body.

After verifying the alignment fix them using the small screws to the hole inside the leg.

Step 6: Fix Foot to Legs

Taking care of the cables as showed in the illustration you should put the cables inside the slots of the body passing thought the hole of the legs.

Once they are in right position use the pointed screws to fix them from the back.

Step 7: Head Assembly

Start from the ultrasound sensor is important to pull out the eyes to the limit.

After putting the Arduino nano in the shield, optionally you can weld the battery holder positive cable to Vin in the board and negative to any GND.

Insert diagonally the both boards together facing the USB conector to the hole in the 3D printed head, then use the last 2 pointed screws to fix it.

Step 8: Electric Connection (Wiring)

Prepare the shield, cables and buzzer.

Then follow the diagram pins numbers and make sure to put them in the right position.

You have at least 4 option to power your Otto:

1. 4xAA alkaline batteries (1.5V each) that connected in series go to Vin pin and Gnd

2. 4xAA rechargeable batteries (1.2V each) that connected in series go to 5V pin and Gnd

3. Just directly from USB cable to your computer or even a power bank

4. External jack connector to use power adapters from 6V up to 12V output

Step 9: Snap the Head and Upload the Code

The head just snaps in, take care of the cables and close it.

Code

otto_by_bluetooth.ino

#include <Otto.h>
#include <Otto_gestures.h>
#include <Otto_sounds.h>

// --- Otto servo pins ---
#define PIN_YL   2
#define PIN_YR   3
#define PIN_RL   4
#define PIN_RR   5
#define PIN_BUZZER 13

Otto Otto;

void setup() {
  Serial.begin(9600);  // Hardware Serial (pins 0 & 1)
  Otto.init(PIN_YL, PIN_YR, PIN_RL, PIN_RR, true, PIN_BUZZER);
  Otto.home();
  Otto.sing(S_connection);

  Serial.println("Otto Ready! Send F,B,L,R,J,D,S via Bluetooth.");
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();
    Serial.print("Command: ");
    Serial.println(cmd);

    switch (cmd) {
      case 'F': Otto.walk(4, 1000, 1); break;
      case 'B': Otto.walk(4, 1000, -1); break;
      case 'L': Otto.turn(3, 1000, -1); break;
      case 'R': Otto.turn(3, 1000, 1); break;
      case 'J': Otto.jump(1, 700); break;
      case 'D':
        Otto.moonwalker(3, 900, 20, 1);
        Otto.moonwalker(3, 900, 20, -1);
        Otto.sing(S_superHappy);
        break;
      case 'S': Otto.home(); break;
      default:  Serial.println("Unknown command"); break;
    }
  }
}

Credits

Webotricks

33 projects • 10 followers

Otto DIY — Build Your Own Robot in One Hour!