compareeHub

ZEROTH-BOT: A TINY OPEN-SOURCE HUMANOID YOU CAN ACTUALLY AFFORD

A palm-of-two-hands humanoid with a hobby-tier parts list — sim-to-real reinforcement learning, vision and speech, first built at a 24-hour hackathon.

by Zeroth Robotics (Jingxiang Mo, Kelsey Pool, Denys Bezmenov and contributors)

FULL CAD BOM FIRMWARE DOCS

RoboticsAI

Built withRaspberry Pi Pico / RP20403D printing

difficulty
●●●●○
time
several weekends
license
MIT
repo
repo ACTIVE832 stars

WHAT YOU’LL NEED

Videos
1
Jump to section

COMPAREE VERDICT

Zeroth-Bot is the most approachable open humanoid on our list — a small biped with a genuinely hobby-tier parts list, first hacked together at a 24-hour hackathon and now an end-to-end sim-to-real RL robot with vision and speech, all MIT-licensed. The brain is a sub-hobby-price Linux single-board computer, which is a big part of why it's affordable. Set expectations on the repo layout: the 'zeroth-bot' repo you land on is a thin umbrella, with the real CAD (OnShape), BOM and assembly guide in the docs repo and sibling repos, and it's an explicitly pre-1.0 project (expect breaking changes). But if you want to build a real walking humanoid without a research budget, this is the friendliest door in.

GOOD TO KNOW

  • —Real open hardware: editable OnShape CAD, an STL zip, a BOM with links and prices, and a photo assembly guide in the docs repo; the BOM is marked not yet finalized and the README now points to the K-Scale docs for the current build guide.
  • —The 'zeroth-bot' repo is a thin umbrella: the software lives in K-Scale's kos-zbot and ksim-gym-zbot repos, and the CAD, BOM and assembly guide in the docs repo.
  • —The ready-to-print STL zip lives in the zeroth-robotics/docs GitHub repo; the editable CAD is on OnShape.
  • —It's a pre-1.0 prototype (public alpha/beta) and needs commercial parts (16 servos, a Milk-V board, IMU, camera)

Parts to buy

11 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • 16 STS3250 serial-bus servosFind
  • Milk-V Duo S boardFind
  • Waveshare bus servo adapterFind
  • RP2040 LCD boardFind
  • 9-DOF IMUFind
  • Milk-V cameraFind
  • RC LiPoFind
  • 12 V to 5 V converterFind
  • MicrophoneFind
  • Small speaker and amplifierFind
  • M3 screws with spring washersFind

BUILDS OF THE WEEK

Five open-source builds worth your weekend, every week.

Checked like this one: what’s really in the repo, what it costs, how hard it is. One email, unsubscribe anytime.

Can I build this?

Printthe body from the STL zip in the docs repo, or export from the OnShape CAD
Buy16 STS3250 serial-bus servos, a Milk-V Duo S board, a Waveshare bus servo adapter, an RP2040 LCD board, a 9-DOF IMU, a Milk-V camera, an RC LiPo, a 12 V to 5 V converter, a microphone, a small speaker and amplifier, M3 screws with spring washers
Tools3D printer, soldering, hex drivers
Skillsintermediate-plus: assembly, Linux, some RL curiosity
Timeseveral weekends
Costband $ — an entry-level humanoid BOM; current prices: creator's docs
SafetyLiPo care and 16 geared servos on a biped — supervise and mind fingers

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Zeroth-01 Status Update1:26

A status update showing the little humanoid.

More builds like this

All projects
ALOHA: The Stanford Robot That Learns From YouRoboticsToddlerBot — Stanford open-source toddler-sized humanoidRobotics3D print this robot arm, show it a task, and it learns to repeat itRobotics

Gallery

Zeroth-01 wavingZeroth Robotics (MIT)
System architectureZeroth Robotics
Joint mapZeroth Robotics
From the assembly guideZeroth Robotics

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the docs (BOM + assembly guide live here)
  2. 2.Watch the update (see it move)
  3. 3.Get the CAD/STL (OnShape + docs-site STL zip)
  4. 4.Explore the electronics + firmware (kos-zbot (robot OS and servo drivers) and ksim-gym-zbot (RL training) from K-Scale, linked as submodules)
  5. 5.Join the Discord (community help)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • The 'zeroth-bot' repo is a thin umbrella — the real CAD, BOM, firmware and sim live in the docs repo and sibling/K-Scale repos
  • The STL files are not in the main zeroth-bot repo — download the zip from the docs repo (or export from OnShape)
  • It's a pre-1.0 prototype (public alpha/beta) — expect breaking changes
  • It needs commercial parts: 16 serial-bus servos (the biggest cost, with prices that vary by seller), a Milk-V board, IMU, camera, battery and audio parts. The BOM is marked not yet finalized.

How is it so cheap?

A hobby-tier BOM: the project says it starts at about 350 dollars, most of it the 16 serial-bus servos, while the Linux brain is a Milk-V Duo S listed at about 10 dollars.

Was it really built in a day?

The first version was built at a 24-hour hackathon (August 2024). It's since grown into an end-to-end sim-to-real RL robot with vision and speech.

Where are the files?

CAD is on OnShape with an STL zip on the docs site; the BOM and assembly guide are in the docs repo; electronics and firmware are in sibling and K-Scale repos.

What does it cost?

Band $ — an entry-level humanoid BOM. The docs have current prices.

Community builds

No community builds yet — be the first, we feature the best ones.

Discussion1

FROM THE COMPAREE TEAM

Instead of a Raspberry Pi, Zeroth-Bot runs its humanoid brain on a Milk-V Duo S — an unusually cheap Linux board. Bold sourcing, or a support headache you'd swap out on day one?

CompareeTEAM2mo agoedited

Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Berkeley Humanoid Lite: an open-source humanoid robot whose actuators are 3D printed

●●●●● · a more capable (and pricier) open humanoid

He built a running humanoid robot in 120 days — and gave away every blueprint for free

●●●●● · a full-size running humanoid

You can 3D-print your own walking Star Wars BD-X droid - fully open-source

●●●●○ · a small legged RL robot

Zeroth Robotics (Jingxiang Mo, Kelsey Pool, Denys Bezmenov and contributors)

Started at a 24-hour hackathon and grew into an affordable, hackable open-source humanoid — MIT-licensed hardware, SDK and simulation — aimed at making real humanoid robotics accessible.

GitHub

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
GitHub repo