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HumanoidK-Scale Labs2025US

Z-Bot (Zeroth Bot)

Small 3D-printed open-source humanoid (~46 cm, 18 motors) from K-Scale Labs, community-developed as Zeroth Bot; sold as Z-Bot at $999 before K-Scale shut down.

orphanedDIYL1 Compiledbuildable

Difficulty index

8.4/13
8.4
Index breakdown
Classhumanoid+5
Cost$125 BOM+0.1
DOF18 DOF+1.8
Parts315 parts+1.5
How the index works

Top of the ladder. This robot lives on the humanoid domains.

Specimen photographs

4 items
  • Z-Bot (Zeroth Bot) studio render, three-quarter front view
    Studio render of the published URDF, the model's zero pose. Geometry only; colours are the model's own materials.Rendered by Hyperspawn from kscalelabs/zeroth-bot (MIT) · Hyperspawn render · source
  • Z-Bot (Zeroth Bot) studio render, side view
    Side view of the same URDF render, the model's zero pose.Rendered by Hyperspawn from kscalelabs/zeroth-bot (MIT) · Hyperspawn render · source
  • 4 s turntable of the URDF studio render.Rendered by Hyperspawn from kscalelabs/zeroth-bot (MIT) · Hyperspawn render · source
  • Z-Bot small humanoid waving outdoors, orange printed shell
    From the zeroth-bot repo.K-Scale Labs (zeroth-bot) · MIT · source

Spec card

7/13 known
Degrees of freedom
18
Height
46 cm
Price
$999 · $999 (2025); community BOM from ~$350
BOM total
$125 · 10/21 lines priced
Part count
315
Actuators
18 servo motors
Sensors
cameras, IMU (per press)

Not in the registry: mass, payload, speed, runtime, battery, compute. Left blank rather than guessed.

What you learn building it

  • +Whole-body control
  • +Dozens of actuators on one bus
  • +Balance and fall handling
  • +Safe bring-up of a full-size machine
  • +FDM 3D printing: 22 parts
  • +Tools used: Bambu-class FDM printer, soldering iron, 1.5 mm hex, 2.5 mm hex, balenaEtcher, microSD card
  • +13 assembly steps across 7 subassemblies
  • +Flashing firmware for Milk-V Duo S (SG2000) running OpenLCH buildroot image (Zeroth-01 BOM), Raspberry Pi 4B running zbot-os-pi4b / kos-zbot (later K-Scale Z-Bot revision), Feetech STS3250 servos (ID/zero config over serial bus, 1 Mbaud), RP2040-LCD-1.28 head display
  • +Testing in simulation (URDF/MJCF) before touching hardware

Openness

90/100
  • publicCAD
  • publicBOM
  • publicFirmware
  • publicSim model
  • publicSoftware
  • not publicPolicies

Score 90/100 computed from what is public: CAD 25, BOM 20, sim 20, firmware 15, software 10, policies 10. Hardware license: MIT. Software license: MIT.

Repos & models

URDF ↗

Build it

Has an ORP build package.
Build it on humanoidrobot.build ↗Files are public but the maker is gone; uncertified, some parts may need alternates.

Simulate

Load it in the browser simulator and train a policy before building.

Open on humanoidrobots.training ↗

Next rung

None. This is the top. Find people building it on humanoidrobots.team.

This is the top of the ladder.

NoteK-Scale Labs shut down in Nov 2025; the repositories (zeroth-bot, MIT) remain public and community-maintained. No maintainer can certify it until someone adopts it. github.com/kscalelabs/zbot does not exist; the project repo is zeroth-bot. ksim-gym-zbot and zbot-policy-walking contain train.py/convert.py only (no checkpoints), so policies=false.

Sources

  1. [1]Zeroth Bot repochecked 2026-09-24
  2. [2]TechEBlog $999 Z-Botchecked 2026-09-24
  3. [3]Humanoids Daily shutdownchecked 2026-09-24