LegoMicroscope is a microscope you can build from bricks and three lenses

Why a Lego microscope is worth building

The stated aim is to provide the instructions and resources of the Lego Microscope for everybody interested, and additionally to hope that people get inspired to introduce extensions or improvements. The project description frames itself as a way to learn about optics and microscopy with a simple to build microscope that needs neither precision optics nor 3D printed parts. The reason that matters is pedagogical, and the Explorer Kit states it directly, asking whether you know the difference between a magnifying glass and a microscope, and noting you might be surprised how simple a microscope is in principle. A device that a child assembles and then looks through pond water with is a different teaching instrument from a diagram of a light path, and the project is a worked argument that the difference between the two is a lens arrangement rather than an instrument category.

Three lenses, and Lego does not sell optics

Almost everything in the build is Lego parts, including the illumination, but the optics had to come from elsewhere because Lego does not offer optics, and in the current state you need three types of additional lens. The ocular is two simple acrylic lenses, diameter 34.5 mm with a focal length of 106 mm, combined with transparent tape, and the current setup uses the lens number 308.OM7. The low magnification objective is a simple glass lens, diameter 18 mm with a focal length of 26.5 mm, lens number 551.OA51, and you are welcome to use any other lenses, with a warning that the dimensions matter for the lens to mount in the objective as the instructions plan. The high magnification objective is the plastic lens of an iPhone 5 camera module, which at the time of writing cost about 2 to 4 euros, and the author acknowledges the waste, since all the electronics are removed, but notes that only the lens is needed.

Two instruction sets, one of them in five parts

There are two sets of instructions. The first is the full plan for building the entire microscope. The second is a plan separated into five parts, A, B, C, D and E, which is used if you want to follow the Explorer Kit, and for that case the project suggests downloading the LEGO package folder with all the information for the kit. The full plan is published as a PDF and the parts are published as a Bricklink ldr list, which you can upload to Bricklink.com to have the bricks sourced if you have no Lego at home. The two sets exist because the two projects are different in kind. Building the whole instrument is a single build, whereas the Explorer Kit is a guided sequence in which each stage ends with something you can look through, and that is the version that has been translated for schools.

LDraw is what makes the plan editable

The instructions were created with LDraw, the free software that allows you to generate basically any Lego building instructions, and the project tells you to download it, follow the install instructions, and then open the CAD file of the plan, where you have the possibility to add features and improve the plan as you think is good, with a reminder to share improvements by creating a fork. This is the decision that turns the project from a set of documents into a piece of infrastructure, because a PDF of building instructions is a snapshot while an LDraw file is a source. It also means the plan can be adapted, which is what the project wants, since it explicitly hopes people will introduce extensions and improvements and asks for forks of the Explorer Kit instructions for kids. The images in the repository show the plan rendering and the build in progress, the caption on the latter being Under construction.

The Explorer Kit, and the sharp tool warning

The Explorer Kit is described as a little guided tour that helps you explore the potential of the Lego microscope, a simple idea to learn about optics while you build it, and the images show a small creature under the lens. There is a safety note attached, and it is the part a parent should read first. For the Explorer Kit, an adult has to prebuild the objectives, because this part is a bit hard for smaller children, and if your kids are already experts you can let them do it, but they need to use some sharp tools to disassemble the smartphone camera module, so the request is to be careful and stay with them to avoid an injury. The warning is not incidental. The high magnification objective is a camera module that has to be taken apart, and that is the one step of the build where a child's hands and a scalpel do not belong together, which is why the plan isolates it for the adult.

Five languages, and a paper

The project is translated, and the translations are the interesting part because they are the ones that decide whether the Explorer Kit is usable in a school. The README exists in English, German, Dutch, Spanish and French, and the Explorer Kit instructions themselves have been generated in English, German, Dutch and Spanish, each as a separate document in the LEGO package folder. The project says it is especially keen on translations of the explorer kit instructions for kids, and that there are many other things you might think you can improve, in which case you should create a fork and upload your changes. Alongside the instructions there is the scientific paper the authors wrote about the Lego Microscope, published on bioRxiv, which is the academic counterpart of the build and the reference for anyone who wants to know whether the design holds up as more than a toy.

What this instrument is, and what it is not

The honest limit is that this is a teaching instrument and not a measuring one. The optics are two acrylic lenses, a simple achromat and the plastic lens out of a phone camera, so the resolution and the numerical aperture are those of a phone camera and a loupe, and the magnification will be modest compared with a laboratory microscope. The project is candid about the waste, that the electronics in the phone module are removed and only the lens is used. What it does offer is the thing a cheap classroom microscope cannot, which is that the student assembles the thing and therefore understands the parts, and the parts are named in the plan, the illumination, the objectives, the eyepiece. The second practical limit is the parts. The Bricklink list exists because most people do not have a pile of Lego, and a build that depends on a specific set of bricks is a build that has to be ordered, which is why the parts list is published in a format Bricklink can consume directly. The third is the state of the project, with a last push on 2026-04-20 and no GitHub releases, so the resources are a snapshot of a design rather than a versioned product, and the licence is Creative Commons Attribution-ShareAlike 4.0, which is the right choice for a document people are meant to translate and adapt.

Editorial conclusion

LegoMicroscope is worth building if you teach, if you work with children and want a hands-on optics lesson that ends with something that actually resolves, or if you want to understand how little of a microscope is precision engineering. It is the wrong instrument for anything quantitative, since the optics are acrylic lens and a phone camera module, so the magnification is limited and the image quality is what a phone sensor gives you, and it is the wrong project if you have no Lego bricks and no way to buy them, because the Bricklink list is a workaround for the same problem. Before you start, read the non-Lego parts section and buy the three lenses first, since the objective has to fit the dimensions the plan expects, and if you are building the Explorer Kit with a child, do the camera module disassembly yourself.

Frequently asked questions

Official sources

1. Issues
2. License: CC-BY-SA-4.0
3. README
4. tobetz/LegoMicroscope on GitHub