YOU CAN BUILD A WALL OF LIQUID MAGNET THAT DRAWS ANIMATIONS IN MID-AIR
252 electromagnets move black magnetic liquid up against gravity to draw animations in mid-air — its builders called it the world's largest open-source ferrofluid display.
DisplaysOpen-hardware
Built withTeensy
- difficulty
- ●●●●●
- time
- months, not weekends
- license
- GPL-3.0
- repo
- repo ACTIVE151 stars
●●●●● · months, not weekends · GPL-3.0 · 151 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
Fetch is a 12 by 21 ferrofluid display: 252 electromagnets under a glass tank pull droplets of black magnetic liquid around to draw animations, all driven by a Teensy 3.6. A group of students at the University of Oslo built it over about two years, and almost everything is published, just spread across places. You will need to fabricate the custom driver PCBs (Gerbers, Eagle files and BOMs are in the creators' separate FetchCADFiles repo), source ferrofluid (the creators used EF-H1), build the glass tank and wooden frame, and tune the magnetic fields until the droplets behave. The Instructables write-up, the Hackaday logs and the Fetch video series explain how they did it, but this is a build story, not a step-by-step recipe, and the firmware README itself warns that it is still under development. The power side is serious: the creators ran the array from a 1200 W server power supply. If you want a months-long showpiece and are comfortable with PCB assembly, embedded code and a lot of tuning, this is a fantastic reference. If you want a weekend build, start with a small prototype matrix, as the creators themselves did.
IN THE REPO
GOOD TO KNOW
- —Firmware repository with code for the Teensy 3.6 controller and display logic.
- —CAD files present for the electromagnet module and mechanical structure.
- —PCB bills of materials are in the separate FetchCADFiles repo; the mechanical parts, magnets and ferrofluid are listed only at a high level on the Hackaday page.
- —Documentation is a build story, not a manual: a 10-step Instructables write-up and Hackaday logs show how it was made, but there is no calibration procedure or ferrofluid tuning guide.
- —Gerbers, Eagle files and schematics for the custom PCBs (V1 and V2) are in the creators' separate FetchCADFiles repository.
- —GPL-3.0 licence — open for commercial use but derivatives must remain open.
- —The project took a group of students about two years to complete.
Parts to buy
6 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
Applied Procrastination documented the build in their own YouTube series (Fetch #1 to #8), including the first full test and assembly.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the firmware README and study the code structure (The firmware README lists the libraries and links to the Instructables, Hackaday and Hackster write-ups; note its own warning that the code is still under development.)
- 2.Locate the PCB and CAD repositories(Gerbers, schematics, BOMs and STEP models are in the creators' FetchCADFiles repository.)
- 3.Source ferrofluid and test the carrier liquid(The right ferrofluid concentration and carrier viscosity are critical — expect to experiment.)
- 4.Fabricate or order the PCBs(Once you have the Gerbers, budget for fabrication and component sourcing.)
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 BOM spreadsheets cover the PCBs only (in the separate FetchCADFiles repo) — magnets, tank, ferrofluid and power supply you still have to spec and source yourself.
- The PCB files live in a separate repo (FetchCADFiles), and V2 boards are not compatible with V1 — make sure firmware, libraries and boards all come from the same version.
- Ferrofluid behaviour is highly sensitive to viscosity, temperature, and magnetic field strength — expect to spend weeks tuning before it looks like the demo video.
- 252 electromagnets running simultaneously need careful power supply design — underestimate this and you will trip breakers or burn traces.
- There is no calibration procedure documented — you will need to write your own tuning scripts or iterate blind.
- Ferrofluid stains are permanent and the fluid is messy during setup — plan your workspace accordingly.
Can I build a smaller version to test the concept first?
Yes, and you should — start with a 3×3 or 4×4 matrix to prove the coil design and ferrofluid behaviour before scaling to 252 pixels.
Where do I get the PCB files?
In the creators' separate FetchCADFiles repository (github.com/AppliedProcrastination/FetchCADFiles), under pcb/V1R2 and pcb/V2R2 — Gerbers, Eagle files, schematics and BOMs.
What ferrofluid should I use?
The creators mention EF-H1 ferrofluid on their Hackaday page; the tank liquid and its behaviour still take experimenting to match the demo.
How much power does this need?
That depends on how many coils you run simultaneously and at what current — the firmware controls timing, but you will need a supply that can handle peak load without sagging voltage.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
252 electromagnets under a glass tank of ferrofluid, all driven by one Teensy. What would you animate on yours first?
Applied Procrastination
A group of students at the University of Oslo, publishing as Applied Procrastination, built Fetch over about two years as a student project and documented it on Hackaday, Instructables and YouTube.
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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.
CompareeTEAM2mo agoedited
Practical notes from our verification: this repository holds the firmware only, and its own README warns that it is still under development and should not be the basis of a hardware project as it stands. The hardware lives elsewhere from the same creators: the FetchCADFiles repository has the Gerbers, Eagle files and BOM spreadsheets for both PCB revisions, there is a 10-step Instructables write-up plus Hackaday and Hackster pages, and the Applied Procrastination YouTube series (Fetch #1 to #8) documents the build. The controller is a Teensy 3.6 driving 252 electromagnets, and the creators name EF-H1 as the ferrofluid. Even with all that, it is not a straightforward step-by-step guide, so replication still takes advanced skills and patience. Ferrofluid stains permanently, so test your setup over surfaces you do not care about. 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.