PUMA: A 3D-PRINTED BENCHTOP MICROSCOPE THAT TAKES PROFESSIONAL OPTICS UP TO 1000X OIL IMMERSION
A retired pathologist published the plans for a battery-powered benchtop microscope you print yourself that takes real lab objectives up to 1000x oil immersion.
ScienceOpen-hardware
Built withArduino3D printing
- difficulty
- ●●●●○
- time
- a fortnight or more
- license
- GPL-3.0
- repo
- repo ACTIVE789 stars
●●●●○ · a fortnight or more · GPL-3.0 · 789 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
PUMA is a 3D-printed microscope designed as a traditional direct-vision benchtop scope rather than a webcam toy. It takes standard RMS objectives with 160 mm tube length, so you can fit second-hand Olympus BH-series or old Zeiss and Leitz glass bought on eBay and get professional image quality — the plastic body holds the optics, it does not replace them. The magnification ceiling is 1000x oil immersion (numerical aperture 1.25), which the author says is enough to resolve bacterial morphology, individual chromosomes and sub-chromosomal detail like FISH signals. It does bright field with full Köhler illumination, fluorescence, dark ground, epi-illumination, polarisation and phase contrast, and adds two features most research scopes lack: an augmented-reality heads-up display that superimposes scale bars, graticules and measurements on the live optical image, and a programmable 240x240 pixel spatial light modulator in the condenser that enables Schlieren phase contrast and Fourier optics methods without special phase objectives. It runs on AA and 9V batteries with no mains, computer or phone required. The documentation is extensive — a Quick Start Guide, a 3D Printing Guide, a Bill of Materials spreadsheet, construction videos on a dedicated YouTube channel, and a peer-reviewed paper. The published 2021 build costs (£47–£173 depending on configuration) already include budget optics; better second-hand objectives push the price up, and printing takes 30 to over 100 hours depending on the build. The main limitations are mechanical: PUMA holds one objective at a time with no turret, and the image wobbles at high magnification if the scope or desk is touched, with some backlash in the focus — the motorised focus option reduces both. If you need a turret, buy a second-hand lab scope. If you want to understand how a research microscope actually works, or need portability and field operation, this is the project. The author also sells ready-made scopes to fund development, so there is a commercial path if you do not want to print.
IN THE REPO
GOOD TO KNOW
- —Full FreeCAD source models, STLs for every part, Arduino code for the AR HUD and spatial light modulator, and a Quick Start Guide PDF, a 3D Printing Guide and a Bill of Materials spreadsheet are all in the repository.
- —Bill of materials is a detailed spreadsheet in the repository with example supplier links; published build costs from 2021 are £47.17 monocular, £79.36 epi-fluorescence, £173.18 advanced trinocular.
- —Licence is GPL-3.0 for files and code, GNU Free Documentation License for the documentation — both permit commercial use with attribution and share-alike.
- —The design is peer-reviewed and published in the Journal of Microscopy (DOI 10.1111/jmi.13043).
- —No clinical or veterinary diagnostic approval — this is for research and education only.
- —Objectives, eyepieces, condenser and some precision hardware (bearings, rods) are not printed — you source second-hand RMS optics or buy new.
Parts to buy
11 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
- RMS objectives (the dominant costFind
- EyepiecesFind
- Abbe condenserFind
- LEDs (white for bright field, UV or blue for fluorescence)Find
- Arduino NanoFind
- GT2 timing beltFind
- Springs and M6 hardware for the focus mechanismFind
- AA and 9V battery holdersFind
- Dichroic mirrors and filters for fluorescenceFind
- M3 fastenersFind
- SpringsFind
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
Introduction to PUMA Microscopy (the advanced 3D printed DIY microscope)13:17
Overview of the project, features and design philosophy by the author. The channel has additional construction and alignment videos.
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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 Quick Start Guide PDF in the repository, then the 3D Printing Guide and the Bill of Materials spreadsheet it points to.(This is better documentation than most commercial microscopes ship with.)
- 2.Watch the Introduction and Overview video to understand which configuration you are building. (Decide monocular, binocular or trinocular based on your use case and budget.)
- 3.Source your optics first — RMS objectives with 160 mm tube length, ideally Olympus BH-series or vintage Zeiss/Leitz from eBay.(The objectives set the image quality. Budget optics work, but second-hand professional glass is worth the hunt.)
- 4.Print the parts in PLA with the PUMA Cura profiles, starting with Z-stage 1 as the Quick Start Guide suggests.(Print times are 30–100+ hours total. Do not rush the focus mechanism parts — they need to be dimensionally accurate.)
- 5.Assemble the base and test the focus mechanism before adding optics.(If the focus is sticky or wobbles, fix it now, not after you have mounted expensive objectives.)
- 6.Follow the Kohler illumination setup video when you mount the condenser and LED. (This is the step that turns a toy into a usable tool. Take your time.)
KNOWN ISSUES
- Buying the wrong objectives. PUMA is built for RMS-thread objectives with 160 mm mechanical tube length (170 mm with the printed extension). Olympus BH-series or old Zeiss and Leitz objectives are right; modern infinity-corrected objectives need a tube lens, and the author says the image quality will not be as good.
- Underestimating the cost of good glass. The published 2021 build costs (£47–£173) include budget optics; the author warns that image quality can only be as good as the optics, so better second-hand objectives and eyepieces will push the total up.
- Skipping Kohler illumination alignment. Without it, you get uneven lighting, glare and no resolution gain from high-NA objectives. The alignment is fiddly, but it is not optional if you want professional images; the author's Köhler illuminator video walks through it.
- Expecting the plastic body to be rigid at high magnification. The author says the image noticeably wobbles if the scope or desk is touched, and the focus has some elastic backlash; the motorised focus option reduces both. If you need a rock-solid stage, buy a second-hand lab scope.
- Ignoring the printing guide. The author specifies a custom Cura profile, orientation and support settings for each part, and printed everything at very high quality; deviating risks parts that do not fit or do not work.
- Assuming you can use it for medical diagnosis. PUMA has no clinical or veterinary approval and is not rated for diagnostic use. It is for research, education and field biology.
Can I use infinite optics or plan achromats?
Not in the standard configuration. PUMA is designed for finite tube length optics (160 mm mechanical tube length) with RMS thread. An inexpensive tube lens lets you use infinity objectives, but the author says image quality suffers and does not recommend it.
What magnification can I actually use?
Up to 1000x total magnification with a 100x oil immersion objective (NA 1.25) and 10x eyepieces. The resolution is set by the objective's numerical aperture, not by magnification — a 1000x with NA 0.25 will be blurry, a 400x with NA 0.95 will be sharp.
Does it take photos?
Yes. The trinocular head has a camera port, any camera that mounts on a standard lab microscope can be fitted, up to three at once, and smartphones work through ordinary eyepiece adapters. At high magnification the image wobbles if the scope or desk is touched; the author says the motorised stage option reduces this significantly.
Can I print it in PETG or ABS?
The author has only ever printed PUMA in standard PLA, and all the printing advice and Cura profiles assume PLA on an Ender 3. Other materials are untested by the author, and the tight-fitting parts are sensitive to dimensional changes. Keep PLA parts away from heat — the guide warns they shrink and distort.
Where do I get the spatial light modulator and AR HUD?
Both are small ST7789-driven TFT modules: the spatial light modulator is a transparent 240x240 TFT in the condenser, and the AR HUD projects a TFT image into the optical path. Both run from the Arduino Nano in the PUMA Control Console. Example sellers are listed in the Bill of Materials spreadsheet.
Do I need oil immersion for everything?
No. Dry 10x and 40x objectives cover a lot of work; the 100x oil immersion objective (NA 1.25) is what lets you see bacterial morphology, chromosomes and sub-chromosomal detail, according to the author. If you do not need that, you can leave it out.
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Discussion1
FROM THE COMPAREE TEAM
The published build cost for the basic monocular is £47.17 (valid around June 2021), and that already includes budget optics — better second-hand objectives can cost more than the rest of the scope. What is the highest magnification you would actually use, and would you hunt for vintage glass or buy new budget optics?
Dr Paul Tadrous
Dr Paul Tadrous is a medical pathologist, now retired from clinical work but still active in research, who spent his career looking down expensive research microscopes. He designed PUMA to bring that quality of optical viewing to people without big budgets — a 3D-printed body that holds professional optics and runs in the field on batteries. The design is peer-reviewed and published in the Journal of Microscopy, and in 2026 he completed a full XYZ CNC stage using NEMA motors and TMC2209 drivers. He also runs OptArc, which sells ready-made PUMA scopes to fund the open-source development.
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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 active (last push September 2026), and the author flags the 2021 v1.0.0 release as out of date, so build from the main branch. The project has a dedicated YouTube channel with construction guides and usage tutorials, a 23-page Quick Start Guide PDF that tells you what to print and what hardware to get, and a bill of materials spreadsheet with example sellers. It is backed by a peer-reviewed paper in the Journal of Microscopy (DOI 10.1111/jmi.13043). The published build costs (£47.17, £79.36 and £173.18 for three example configurations) were valid around June 2021 and already include budget optics, so treat them as a starting point rather than today's prices; better second-hand objectives cost extra. PUMA works best with 160 or 170 mm tube-length RMS objectives; infinity objectives can be used with an inexpensive tube lens, though the author notes the image quality will not be as good. Printing alone can run past 100 hours for the more complex configurations. If you would rather not build, the author also sells ready-made PUMA scopes through OptArc. 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.