This is the Little Man Builds Kids Traffic Light STEM Kit: an open-source KiCad project for building a real working traffic light with custom PCBs, ESP32-S3 firmware, wiring, and optional mechanical parts.

Yes, it is technically “just” a traffic light. But that is also what makes it great.

Red means stop. Green means go. Yellow means “make a questionable decision and then pretend you planned it.” Kids understand it instantly, which makes it a perfect excuse to sneak in electronics, soldering, firmware, PCB design, debugging, and the occasional quiet moment where an adult says, “Interesting,” while absolutely not understanding why the LED is backwards.

Important: looking for just the lamp boards?

This PCBWay project is for the full kit / reference electronics build. If you only want the simple red, yellow, and green traffic light lamp boards, there is a separate PCBWay shared project for the lamp boards only version.

That version is the better choice if you already have your own controller board, Arduino, ESP32, Raspberry Pi Pico, classroom setup, or a suspiciously organized drawer full of microcontrollers. This version is the more complete reference build, including the ESP32-S3 electronics path, firmware, documentation, and supporting design files.

Why I made it

A lot of beginner electronics projects are either too abstract, too fragile, or involve one lonely LED blinking on a breadboard while everyone politely pretends to be amazed. I wanted something more visual, more buildable, and more fun.

A traffic light gives kids something they immediately recognize. It gives beginners a clear reason to learn about LEDs, polarity, soldering, wiring, timing, code, and what happens when the thing that should be green is very confidently not green.

The aim was not to make the world’s most complicated traffic light. The aim was to make a small open-source hardware project that people can actually build, understand, modify, manufacture, and improve without needing a secret lab, a corporate budget, or a degree in “why is this connector upside down?”

Build paths

This project is deliberately flexible, because not everyone wants to build the same version and not everyone has the same amount of time, tools, or emotional stability around crimp connectors.

1. Lamp boards only — Use the red, yellow, and green lamp boards with your own controller. This is available as a separate PCBWay shared project and is ideal if you only want the traffic light LED boards.

2. Full reference electronics — Use the ESP32-S3 reference electronics together with the traffic light boards. This is the version represented by this PCBWay project.

3. Custom mechanical build — Use the included mechanical files, adapt them, or build your own housing from 3D prints, wood, cardboard, laser-cut panels, or whatever material is currently closest to your workbench.

The project is designed to be useful whether you build the full version or just borrow the bits that make sense for your own project.

What you can learn

Depending on how deep you want to go, this project can help beginners explore:

• KiCad schematic and PCB design

• LED boards and polarity

• Soldering and assembly

• Wiring and connector checks

• ESP32-S3 firmware

• Traffic light timing logic

• PCB manufacturing files

• BOM and centroid preparation

• Mechanical mounting and enclosure design

• Debugging, also known as “learning, but with more blinking”

It is simple enough to understand quickly, but complete enough to show the path from idea to real manufactured PCB.

Repository structure

The full GitHub repository includes the design files, firmware, documentation, and build resources.

The project is organized into:

• 01_Electronics — KiCad files, schematics, PCB files, BOMs, and manufacturing exports

• 02_Mechanical — CAD, DXF, STEP, layout, and mechanical build information

• 03_Firmware — ESP32 / PlatformIO firmware

• 04_Guides — build guide, shopping guide, and LED resistor notes

The cover images on this PCBWay page shows the main PCB design. All source files, manufacturing files, build notes, and project documentation are available in the GitHub repository.

Manufacturing and assembly

This project includes manufacturing-ready files such as the KiCad design files, BOM, and centroid data. It is intended to support both learning and practical manufacturing:

• Order the PCB and assemble it yourself

• Use PCB assembly where appropriate

• Study the files and adapt the design

• Build only the parts you need

• Discover that documentation is what future-you desperately wishes past-you had written

Some parts may still be better suited to hand assembly depending on the build path, especially where the goal is education and soldering practice.

License note

PCBWay’s license dropdown does not currently include the exact hardware license used by the GitHub repository, so this PCBWay page uses TAPR Open Hardware License as the closest available open-hardware option in the form.

The official project licensing is defined in the GitHub repository:

• The hardware design is licensed under CERN-OHL-S-2.0.

• The firmware/software is licensed under the MIT License.

In normal maker English: you can study it, build it, modify it, manufacture it, and improve it. For the hardware design, the GitHub repository license is the source of truth. If you remix the hardware, please keep the open-hardware spirit alive and share your changes properly.

Basically: build cool stuff, just do not quietly turn the open-source bit into a locked box with better branding.

Safety and responsibility

This is an open-source maker project, not a certified children’s product, toy, or commercial safety device. If children are involved, adults should handle soldering, wiring, tools, power checks, and final inspection.

Before powering anything:

• Check the voltage

• Check the polarity

• Check the connector pinouts

• Inspect the solder joints

• Do not connect mains voltage(!)

• Do not leave powered maker projects unattended

Build cool things. Try not to make the magic smoke part of the curriculum.

Who this is for

This project is for:

• Parents and kids building something together

• Schools, STEM clubs, and makerspaces

• Beginners learning soldering, LEDs, firmware, and KiCad

• Makers who want a small open-source PCB project to modify

• Anyone who thinks a tiny working traffic light is more fun than it probably has any legal right to be

If you build this

If you make one, modify one, break one, fix one, or somehow turn it into something I did not expect, I would love to see it.

Feel free to reach out on any of the below platforms:

• GitHub: https://github.com/littlemanbuilds/Kids_Traffic_Light

• YouTube: https://www.youtube.com/@MoreLittleManBuilds

• YouTube: https://www.youtube.com/@LittleManBuildsOfficial

• Discord: https://discord.gg/9xtMYyYeCT

The best support is simple: build something, improve something, and share what you learned.

Build deliberately.

/Darren