YOU CAN BUILD A WALL OF 80 STEEL BALLS THAT FLOAT AND RIPPLE LIKE LIQUID METAL
80 polished steel balls hanging on independent cables, each driven by its own motor to draw waves and shapes in mid-air — museum-grade kinetic art you can actually build.
by Andrew Kotite and Ben Oztalay
DisplaysRobotics
- difficulty
- ●●●●●
- time
- several weekends
- license
- MIT
- repo
- repo ACTIVE7 stars
●●●●● · several weekends · MIT · 7 stars · repo ACTIVE
WHAT YOU’LL NEED
- Dev board / microcontroller — runs the project firmware
- Soldering kit + basic tools — one-time buy, serves every future build
Partner
COMPAREE VERDICT
This is one of the most visually striking kinetic sculptures in the open-source catalogue, and the control code is all there: motor coordination, LED sync, animation patterns, and a Python simulator to test sequences before running them on the real hardware. What is missing is the hardware build guide. You have photos, build logs, and a description of the motors (geared DC with encoders, 1.5m range, 0.5mm precision), but no CAD for the frame, no dimensioned drawings, and no bill of materials. You will be reverse-engineering the mechanical side from the Hackaday logs and the photos. If you have done large-scale motorised installations before — or you are willing to spend several weekends working out cable routing, motor mounting, power distribution, and frame rigidity on your own — the code will get you the rest of the way. If you have not, this is not the first kinetic project to start with. The single biggest trap is underestimating the mechanical complexity: 80 motors means 80 points of cable friction, 80 encoders to calibrate, and a frame that must hold precision over more than a metre of travel while looking clean enough for a gallery wall. The software is elegant; the hardware is a full custom build.
IN THE REPO
NOT IN THE REPO
- —Firmware and simulator code present (Python, Raspberry Pi, Arduino)
- —No CAD files for the frame, motor mounts, or cable routing
- —No bill of materials — you are reverse-engineering the hardware from photos and logs
- —Build logs on Hackaday.io describe the geared motors, encoders, RGB LED strips, cable setup, and control architecture
- —MIT license allows commercial use
- —This is a finished installation — the repository is the choreography code and simulator, not a step-by-step build guide
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the Hackaday.io build logs to understand the motor choice, cable setup, and control architecture (This is your primary reference — the logs describe the hardware decisions and installation process.)
- 2.Clone the simulator and control code (Run the Python simulator to see how animations are defined and test patterns before building hardware.)
- 3.Source motors with encoders that match the travel range and precision requirements(The logs describe 1.5m travel and 0.5mm precision — you need geared motors with encoders; expect significant cost and lead time for 80 units.)
- 4.Design or adapt a frame to hold 80 motors in the arrangement you want(No CAD is provided — you are building this part yourself. Aluminium extrusion is a common choice for rigidity and modularity.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
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KNOWN ISSUES
- No CAD files or BOM — you are reverse-engineering the entire mechanical build from photos and logs, which is the single biggest time sink.
- 80 motors with encoders is a large upfront cost and a long lead time if you are sourcing them yourself — budget for both.
- Cable routing and friction tuning is where most of the build time goes — one sticky pulley or misaligned cable and that ball will not move smoothly.
- Power distribution for 80 motors plus 172 LEDs is non-trivial — plan your supply topology before you start wiring.
- The frame must be rigid enough to hold precision over 1.5m of cable travel while looking gallery-clean — a wobbly frame will show in every animation.
- Calibration is per-motor, per-encoder — expect a full day just getting all 80 balls to home correctly and move in sync.
Is there a bill of materials?
No. The Hackaday logs describe the motor type and general setup, but you will be sourcing and speccing everything yourself.
Can I build a smaller version to test the concept?
Yes, and that is the recommended path — start with a 4×4 or 5×5 grid to prove the motor control, cable routing, and animation code before committing to 80 units.
What motors did they use?
The logs mention geared DC motors with encoders capable of 1.5m travel and 0.5mm precision, but no specific part number is given — you will need to find equivalent motors that meet those specs.
How loud is it?
80 motors running simultaneously will produce audible hum and whir — this is not silent kinetic art, though the logs do not quantify noise level.
Can I run this outdoors?
The design assumes indoor installation — motors, electronics, and steel balls are not weatherproofed, and wind will interfere with cable tension and positioning.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
80 motors, 172 LEDs, and 1.5 metres of cable travel per ball — all without a published BOM or CAD. Would you reverse-engineer the hardware to build one, or start with a smaller proof-of-concept first?
Andrew Kotite and Ben Oztalay
Andrew and Ben built this kinetic sculpture as a large-scale installation piece, combining precise motor control with choreographed lighting to create animations that seem to float in mid-air. The project grew from earlier experiments with smaller kinetic displays and was designed to be museum-grade in appearance and movement quality.
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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.
CompareeTEAM1mo agoedited
Practical notes from our verification: the repository is the control code and Python simulator, not the mechanical build — CAD and BOM are entirely absent, so you are working from the Hackaday logs and photos to reverse-engineer the frame, motor mounts, and cable routing. The logs are detailed enough to understand the architecture (geared motors with encoders, 1.5m travel, Raspberry Pi + Arduino coordination), but this is not a weekend build — it is a multi-weekend custom installation project. The single biggest time sink will be mechanical: getting 80 cables routed cleanly, 80 encoders calibrated, and a frame rigid enough to hold precision over more than a metre of movement. If you have done large-scale motorised art before, the code will get you the rest of the way. If you have not, build a 4×4 test rig first.