OpenBot DIY components from the official build guide · OpenBot contributorsSource ↗

Image credits and source versions

Two-wheel OpenBot variation featured in the source README ↗ · OpenBot contributors · MIT
Cardboard-chassis OpenBot variation featured in the source README ↗ · OpenBot contributors · MIT

CAIBI ASSESSMENT

OpenBot DIY

CAIBI VERDICTBUILD IT

An open wheeled robot that reuses a smartphone for camera, compute and higher-level robotics while an Arduino Nano or ESP32 handles the motors and low-level sensors.

See what the build involves Original source ↗

Build or buy?

Compare the documented build with the purchase reference.

Build it yourself

Known parts cost£37Build total not establishedRobot body only; smartphone, printing and charging extra

Time: Not published. Treat printing, electronics assembly, firmware/app setup and physical testing as separate stages rather than a single quick build.
Difficulty: 3/5
Physical processes: 3D printer or print service · Soldering and electronics tools · Android smartphone · Computer for firmware and app setup

See build requirements →

Purchase reference

Buy price referencePrice not checkedOpenBot RTR-TT / RTR-520

Check the source for the exact model, availability and what is included.

Check comparison evidence →

Purchase comparison not yet priced

What the prices cover

The current OpenBot repository and project site still describe the DIY robot body as about $50. A third-party BOM with component links checked on 31 Aug 2026 estimates roughly $50 to $80. CAIBI uses the source headline as a baseline and not as a guaranteed all-in first-build total.

Includes: Core low-cost wheeled robot-body hardware represented by the source headline; Arduino Nano or supported microcontroller bridge, motors and simple drive electronics in the selected DIY route.

Not included: Android smartphone; 3D printer or print service and filament; Battery charging equipment and shipping; Optional sensors, custom PCB route and upgrades; Controller hardware where separately required; Assembly, software setup and policy-training time.

Build evidence recorded 5 Sep 2026. Currency conversions are approximate.

The current OpenBot body documentation links ready-to-run RTR-TT and RTR-520 products on Amazon. The DIY route still carries an about $50 robot-body headline and a current third-party BOM estimate of $50 to $80, but it also assumes a suitable smartphone and fabrication access. Without a verified current regional RTR price and matched inclusions, CAIBI treats the routes as not like-for-like and does not publish a saving.

GLOBAL purchase/source reference ↗GLOBAL purchase/source reference ↗

BUILD AT A GLANCE

Source view and main parts

Check the source ↗

**Two-wheel OpenBot variation featured in the source README**OpenBot contributors · MITSource and version ↗

OpenBot DIY components from the official build guide · OpenBot contributors ↗

PHYSICAL BUILD9 key parts or groups

No.	Source specification
01	Arduino Nano or supported ESP32 development board as the low-level robot controller
02	Four TT gear motors with wheels for the standard DIY body
03	L298N motor driver for the simple DIY electronics route or the project custom PCB route
04	Three 18650 cells and a three-cell holder for the standard DIY body
05	USB OTG cable matched to the smartphone connection
06	Printed robot body and adjustable phone mount or a compatible alternative chassis
07	M3 fasteners
08	Optional wheel-speed sensors
09	Android smartphone for the main documented app and vision route

Full source specifications

Arduino Nano or supported ESP32 development board as the low-level robot controller
Four TT gear motors with wheels for the standard DIY body
L298N motor driver for the simple DIY electronics route or the project custom PCB route
Three 18650 cells and a three-cell holder for the standard DIY body
USB OTG cable matched to the smartphone connection
Printed robot body and adjustable phone mount or a compatible alternative chassis
M3 fasteners, Dupont wiring and small mechanical hardware
Optional wheel-speed sensors, ultrasonic sensor, indicators, switch and OLED display
Android smartphone for the main documented app and vision route

TOOLS / PROCESSES4 involved

3D printer or print service
Soldering and electronics tools
Android smartphone
Computer for firmware and app setup

The real-world work

YOU STILL HAVE TOThe real-world work

Choose a body variant that fits the available printer, phone and intended terrain
Print or fabricate the chassis and phone mount, or use a compatible alternative robot-car chassis
Source quality 18650 cells and use an appropriate charging and handling route
Solder and wire the motors, motor driver or PCB, microcontroller, battery and selected sensors
Secure the phone so it cannot leave the mount during acceleration, impacts or turns
Flash the exact hardware profile and prove steering, stopping and sensor directions at low consequence
Test remote and autonomous behaviour in a clear controlled area before increasing speed or complexity
Treat learned or vision-based behaviour as fallible and remain responsible for people, pets, property and the robot around it

THE BUILD SEQUENCE

How it comes together

1Preparation

Pick the exact OpenBot route
Choose the standard DIY body, smaller Lite body, RC-truck conversion, multi-terrain vehicle or another supported chassis. Do this before ordering because the mechanics, firmware profile and some electronics differ.
AI + YOU
Print or prepare the chassis
Use the source body that fits the available build plate, or start from a compatible robot-car chassis. Print the phone mount as part of the system rather than treating the phone as a loose accessory.
YOU
Build the drive electronics
Wire the motors and L298N DIY route or build the custom-PCB route, then add the battery holder and only the sensors required for the chosen build. Keep polarity and hardware-profile differences explicit.
YOU

2Build and assembly

Inspect power and phone retention
Use sound 18650 cells, an appropriate charging route and insulated wiring. Verify that the battery and phone cannot shift into moving parts or leave the chassis before powering the wheels.
YOU
Flash the correct low-level firmware
Select the exact OpenBot hardware configuration in the source firmware, then prove motor direction, stopping, wheel-sensor direction and optional ultrasonic behaviour before connecting higher-level autonomy.
AI + YOU
Set up the phone software
Install the supported app route and establish the phone-to-microcontroller connection. Confirm camera framing and physical phone angle because poor framing directly reduces what the vision system can use.
AI + YOU

3Configure and test

Prove manual control first
Drive at low speed in a clear area and verify steering, braking, battery readings and any fitted sensors. Fix mechanical pull, reversed motors, loose wiring and wheel-slip problems before testing learned behaviour.
YOU
Add autonomy as an experiment
Only after manual control is predictable should you try person following, navigation, Playground behaviours or a trained driving policy. Record failures and keep a human able to stop the robot because perception and learned control can be wrong.
AI + YOU

Benchmark this project

Use the OpenBot DIY prompt. Compare what different models deliver, then add what happened when you tried it.

Try this benchmark

View the project prompt

CAIBI adaptation · Prompt 1.0 · Project source

Prompt for OpenBot DIY

CAIBI project benchmark: OpenBot DIY
Prompt version 1.0

Help me build OpenBot DIY using the existing creator project at https://github.com/ob-f/OpenBot. This is a CAIBI benchmark adaptation of the project build brief, not a claim about how the creator used AI.

Project context:
- An open wheeled robot that reuses a smartphone for camera, compute and higher-level robotics while an Arduino Nano or ESP32 handles the motors and low-level sensors.
- Build context: Arduino Nano or supported ESP32 development board as the low-level robot controller; Four TT gear motors with wheels for the standard DIY body; L298N motor driver for the simple DIY electronics route or the project custom PCB route; Three 18650 cells and a three-cell holder for the standard DIY body; USB OTG cable matched to the smartphone connection; Printed robot body and adjustable phone mount or a compatible alternative chassis; M3 fasteners, Dupont wiring and small mechanical hardware; Optional wheel-speed sensors, ultrasonic sensor, indicators, switch and OLED display; Android smartphone for the main documented app and vision route.
- Where AI helps: Navigate the current DIY, Lite, RC-truck, multi-terrain and ready-to-run source routes, Map the BOM to the selected body and DIY or custom-PCB electronics route, Explain Arduino Nano and ESP32 firmware configuration without mixing hardware profiles, Help diagnose USB OTG, serial, motor-direction, sensor and GPIO problems from observed behaviour, Adapt firmware, controller or app code for custom controls and sensors, Help plan Playground behaviours, data collection and policy-training experiments, Review logs and test results while keeping physical safety checks with the builder.
- Physical work: Choose a body variant that fits the available printer, phone and intended terrain, Print or fabricate the chassis and phone mount, or use a compatible alternative robot-car chassis, Source quality 18650 cells and use an appropriate charging and handling route, Solder and wire the motors, motor driver or PCB, microcontroller, battery and selected sensors, Secure the phone so it cannot leave the mount during acceleration, impacts or turns, Flash the exact hardware profile and prove steering, stopping and sensor directions at low consequence, Test remote and autonomous behaviour in a clear controlled area before increasing speed or complexity, Treat learned or vision-based behaviour as fallible and remain responsible for people, pets, property and the robot around it.
- Main limitation: The headline $50 is a robot-body figure, not a guaranteed first-build total. You still need a suitable smartphone, printed or alternative chassis, three 18650 cells, safe charging, electronics assembly and time to configure the firmware and app. Autonomous person following and navigation are software capabilities, not a safety system. The source itself limits the hardware to educational and experimental use and puts responsibility for safe construction and operation on the builder.

Read the source first. Use its published design, files, dimensions and parts as the baseline; do not redesign it unless a missing detail requires a clearly labelled proposal. If you cannot access a source or verify a revision, say so.

Provide one practical build package:
1. Design and files: explain the source design, link the original editable files, and identify missing files or modifications.
2. Parts and fabrication: give quantities, exact variants and compatibility, plus a cutting or printing list where applicable. Preserve source dimensions; flag anything unconfirmed.
3. UK and US purchasing: direct product links, checked dates, stock, pack sizes, taxes, delivery and regional costs. Mark unverifiable details as unknown; do not invent links, prices or availability.
4. Assembly: an ordered guide covering fabrication, fitting, wiring or software as applicable, setup, checks and troubleshooting.
5. Cost and time: separate parts, fabrication, delivery, hands-on time and machine time, with assumptions and exclusions.
6. Function and ease: a test plan for the project's stated purpose, likely difficulties, required skills and any corrections or limitations.

Keep source facts, your proposals and items needing physical verification distinct. An estimate is not a measured build result. Do not claim to have built or tested hardware. Include failed attempts and omissions. If a section does not apply, say why.

Use the source as accessed during this run and record its revision or access date. The prompt is fixed; the linked source can change.

Open and copy prompt →

Benchmark results 0

No reviewed results yet for OpenBot DIY. Add the first result →

AI IN THIS PROJECT

Get AI help on this build

CAIBI · AI CAN HELP

AI can help with

Navigate the current DIY, Lite, RC-truck, multi-terrain and ready-to-run source routes
Map the BOM to the selected body and DIY or custom-PCB electronics route
Explain Arduino Nano and ESP32 firmware configuration without mixing hardware profiles
Help diagnose USB OTG, serial, motor-direction, sensor and GPIO problems from observed behaviour
Adapt firmware, controller or app code for custom controls and sensors
Help plan Playground behaviours, data collection and policy-training experiments
Review logs and test results while keeping physical safety checks with the builder

CAIBI · AI CAN'T DO

You still need to

Choose a body variant that fits the available printer, phone and intended terrain
Print or fabricate the chassis and phone mount, or use a compatible alternative robot-car chassis
Source quality 18650 cells and use an appropriate charging and handling route
Solder and wire the motors, motor driver or PCB, microcontroller, battery and selected sensors
Secure the phone so it cannot leave the mount during acceleration, impacts or turns
Flash the exact hardware profile and prove steering, stopping and sensor directions at low consequence
Test remote and autonomous behaviour in a clear controlled area before increasing speed or complexity
Treat learned or vision-based behaviour as fallible and remain responsible for people, pets, property and the robot around it

Original source AI use and prompts

SOURCEThe original project does not publish an AI prompt

The prompts below are CAIBI helpers for this build. They are not presented as instructions from the creator.

CAIBI STARTING PROMPTS

Copy a prompt for this build

Each prompt tells AI to keep the original project source as the reference and to flag anything you must verify on the real build.

Ways to take it further

AFTER THE FIRST BUILD

Ways to take it further

Standard OpenBot DIYOpenBot Lite education bodyRC-truck conversionMulti-Terrain VehicleCustom PCB electronicsDIY L298N electronicsReady-to-run RTR-TT / RTR-520 source route

More routes and resources

OTHER WAYS TO GET THERE

You do not have to follow one route.

ORIGINAL BUILDFollow the creator route

Use the published files and instructions as the baseline.

OUTSOURCE A PROCESSGet specialist fabrication done

You do not necessarily need to own every capability used here: 3D printer or print service, Soldering and electronics tools, Android smartphone, Computer for firmware and app setup.

ALTERNATIVE PROJECTSesame Robot

A printable ESP32 quadruped using eight servos, an expressive OLED face and open animation/control software.

REVIEWED RESOURCES

Useful places beyond the main source

GITHUB REPOOpenBot canonical source

Current canonical OpenBot repository for robot bodies, firmware, Android/iOS software, controllers, training and the Playground. The repository was pushed in August 2026.

DOCSOpenBot DIY body guide

Official body variants, required and optional components, DIY versus custom-PCB routes, wiring and physical assembly instructions.

DOCSOpenBot firmware guide

Official Arduino Nano and ESP32 firmware routes with hardware-configuration selection and low-level motor/sensor behaviour.

DOCSOpenBot research paper

Peer-reviewed ICRA 2021 project paper documenting the smartphone-as-robot-brain architecture, roughly $50 robot body and controlled person-following/autonomous-navigation experiments.

DOCSCurrent third-party BOM check

Third-party OpenBot BOM with component links verified in August 2026 and a $50 to $80 materials estimate. Useful as current price context, not an official OpenBot quote.

DOCSIndependent OpenBot build series

Independent physical build and test series reporting successful app setup and autonomous operation while surfacing practical phone-camera positioning and build considerations.

SOURCE · CAIBI · BUILDERS

What supports the verdict

SOURCEOpenBot Foundation

OpenBot is current. The canonical project now lives at ob-f/OpenBot, is not archived and was pushed on 26 Aug 2026. The current source still maintains DIY, Lite, RC-truck, multi-terrain and ready-to-run body routes plus firmware, mobile apps, control and policy tooling. CAIBI retains the older 2021 paper as foundational evidence while using the current repository and 2026 BOM checks for lifecycle and cost context.

Open source ↗

CAIBIBUILD IT

OpenBot makes unusually good use of hardware many people already own. The phone supplies a camera, IMU, compute, display and network connection, while the robot body stays comparatively cheap and understandable. The source is still active in 2026, supports several body variants and exposes the full stack from motor firmware through higher-level autonomy. It is strongest as an education, experimentation and custom-robot platform rather than as a polished domestic appliance.

Evidence: Strong

BUILDERSNo published reports yet

Actual time, cost, changes and outcomes appear here after submitted builds are reviewed.

Be the first builder to report ↓

Leave a build review

HAVE YOU MADE THIS?

Leave a build review.

First-hand evidence improves the assessment

What we want to know

What happened when you actually tried to make it.

Did it work?
Actual time and cost
What did you change?
What was harder than the source suggested?
Would you build it again?