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YOU CAN 3D PRINT YOUR OWN MRI SCANNER

OSI² ONE — an open-source 50 mT MRI scanner that images heads and limbs; its little sibling OSII Mini is a 3D-printed Halbach magnet with 396 cubes built for teaching.

by OSI2 / Open Source Imaging initiative

FULL CAD BOM FIRMWARE DOCS

Medical-devicesScientific-instruments

Built with3D printing

difficulty
●●●●●
time
months
license
CERN-OHL-W-2.0
repo
repo ACTIVE108 stars

WHAT YOU’LL NEED

Videos
1
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COMPAREE VERDICT

This is not a weekend build — it is an expedition. The Open Source Imaging initiative has published the full design of OSI² ONE, a 50 mT low-field MRI whose developers have imaged brains and limbs in vivo, and the repository linked here is OSII Mini, Utrecht University's educational version for student teams: a 3D-printed Halbach frame with a 120 mm bore holding 396 12 mm magnets, which the team puts at around 1,200 euros for a completed magnet. From there you still need shimming, gradient coils, RF coils and an MRI console such as the open OCRA on a Red Pitaya. For most people this is a page to read rather than a build, and even then it is fascinating to see that MRI is no longer a black box. If you are serious about building, start with the Halbach magnet chapter: it is the heart of the machine.

GOOD TO KNOW

  • —This is full open documentation, not a 'print and play' kit — even the educational OSII Mini magnet needs 396 NdFeB magnets and serious metrology

Parts to buy

3 items

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

  • NdFeB magnets396 for the OSII Mini magnet, about 1,200 euros for a completed magnet per the teamFind
  • Gradient and RF coilsFind
  • Amplifiers and an MRI consoleFind

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Can I build this?

PrintHalbach magnet frame + formers — large FDM prints
BuyNdFeB magnets (396 for the OSII Mini magnet, about 1,200 euros for a completed magnet per the team), gradient and RF coils, amplifiers and an MRI console (the docs list Magritek's Kea2 or the open OCRA on a Red Pitaya)
Tools3D printer + electronics workshop + measurement gear
SkillsSolid electronics and RF basics, careful 3D printing and magnet assembly, and the patience for methodical field mapping and shimming
Timemonths
CostExpensive: the team puts a completed OSII Mini magnet at around 1,200 euros, before shimming magnets, gradient and RF coils, amplifiers and an MRI console. There is no full bill of materials in the repository.
SafetyVERY strong magnets — pacemaker/implant hazard, pinch injuries; keep tools and cards away

Very strong magnets — keep away from pacemakers, cards and fingers.

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

Videos

OSI² ONE: An Open Source Low-Field MRI Scanner11:56

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Gallery

The finished Halbach magnetLilisProtoLab / Utrecht
Halbach frame during the buildLilisProtoLab
Magnet ring close-upLilisProtoLab
Official OSI² ONE feature imageopensourceimaging.org

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 project overview docs (understand the architecture first)
  2. 2.Halbach array chapter(the heart of the machine)
  3. 3.Join the Open Source Imaging community (builders + researchers chat on Matrix)

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

  • Magnet field calibration and temperature drift are the hard parts — budget time for shimming
  • It's low-field (~50 mT): images are genuinely useful but noisier than clinical 1.5 T machines
  • The linked GitHub repo is the educational 'OSII Mini' — the full-scale OSI² ONE lives on gitlab.com/osii.
  • Shimming the magnet field is the real challenge; each array ends up unique.

Is it safe?

The field is ~50 mT — about 30× weaker than a hospital MRI. Still: strong magnets, implant and pinch hazards apply.

Are the images actually usable?

For research and education, yes: the 50 mT Halbach design behind OSI² ONE has been used to image brains and limbs in vivo, as in the paper linked on this page. The educational OSII Mini in the linked repository has a 120 mm bore, so it is for smaller samples and teaching. Neither is a clinical diagnostic device.

Can one person build it?

In principle yes, in practice it's a team/lab project. Join the community — nobody builds this alone.

Is this repo the actual OSI² ONE?

Not exactly — the GitHub repo we link is 'OSII Mini', an educational 120 mm version from Utrecht. The full clinical-scale OSI² ONE documentation lives at gitlab.com/osii. Both are worth exploring.

How homogeneous is the field?

Every Halbach array is unique after shimming — builders aim to get inhomogeneity from ~15,000 ppm down under 3,000 ppm. It's the hard, patient part.

Community builds

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

Discussion1

FROM THE COMPAREE TEAM

Every hand-built Halbach array ends up unique — builders shim field inhomogeneity from around 15,000 ppm down under 3,000. Would you sign up for that kind of patient, invisible calibration work?

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.

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OSI2 / Open Source Imaging initiative

An open-science community of MRI researchers publishing the full design of a working low-field MRI so any lab can build and improve it.

GitHub Web

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.
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