Most smartwatches arrive sealed shut. Huy Vector (HVT Lab) built a brass esp32 smartwatch that does not. His watch sits inside a brass cage that looks like it belongs on a Victorian airship, and every wire and solder joint stays in view.
The brass esp32 smartwatch tells time, pulls iPhone notifications over Bluetooth, and switches between watch faces. Notebookcheck reports that the parts cost under $10 in total, and the modder’s website lists every component. All the components can be ordered for under $10, and the modder’s website lists them with links.
The core parts of this esp32 smartwatch are an ESP32-C3 Super Mini development board, a 1.3-inch OLED display, a three-way button, and a 3.7-volt battery. The battery charges through the board’s USB-C port. Notebookcheck also notes that the build takes patience and some prior experience with a soldering iron and ESP32 boards.
Building the brass esp32 smartwatch case and circuit
The build starts with the display. Huy cuts the four corners off the OLED’s circuit board so it fits inside the frame. He then replaces the stock pin headers with 1mm copper wire.
Next, he bends 2mm brass tubing into two matching frames and seals each one with solder. Thinner 1.5mm tubes connect the front and back halves. The brass does double duty as the case and as a conductive path.
The battery’s negative lead and the ESP32-C3’s ground pin both solder directly to the brass. That turns the entire cage into one ground connection. Nothing needs a separate return wire.
A slide switch sits between the battery’s positive terminal and the board’s 5V pin. One flick cuts power. The project’s wiring diagrams show every connection, so there is no guesswork about where each lead goes.
The ESP32-C3 Super Mini measures about 22.5 by 18mm, or roughly 0.89 by 0.71 inches. In that footprint it packs a 160MHz RISC-V processor, 4MB of flash storage, and Bluetooth 5. The OLED and the DS3231 clock module share two data lines, which keeps the wiring compact.
The DS3231 keeps accurate time while the watch is switched off. The USB-C charging board grounds itself through its connector shell, so only its positive lead needs a separate wire. The strap is 20mm, or 0.79 inches, wide.
Water resistance is where the sources differ. Huy applies a water-resistant coating to the brass esp32 smartwatch, and his video shows the watch surviving a dunk in a glass of water. Notebookcheck describes the open brass case as not fully waterproof, though the coating survived a brief immersion during its test.
From a 2013 open-source watch to a brass case
The firmware descends from the N|Watch, an open-source DIY wristwatch that Zak Kemble published in September 2013. Kemble fit animated menus, alarms, games such as Breakout, and a flashlight mode into an ATmega328P chip with 32KB of program space. He switched to a 1.3-inch OLED after a 0.96-inch screen left too little room for his interface.
Kemble’s list of future improvements ended with a question: “A case of some sort?” More than a decade later, Huy’s brass cage answers it. His NWatch C3 port moves the code onto hardware with roughly 125 times the program space of the original chip.
The port adds iPhone notifications through Apple’s Notification Center Service. Flashing the firmware requires no coding. It loads from Chrome or Edge over a USB cable. The full source code is also available, so anyone can change a watch face or rework the button layout.
The firmware ships with five named faces: RAIN, MATRIX, BIGTIME, CUBE, and an analog option labeled CLOCK. An on-screen readout labeled SLP looks like the sleep timeout Kemble built into the original. Treat that match as an observation from the video, not a confirmed feature.
Other builds with the same approach
Huy’s Pocket AI Assistant packs an ESP32-C3, a 0.96-inch OLED with animated eyes, a microphone, and a speaker into a brass frame about the size of two fingers. The device runs on Xiaozhi, an open-source chatbot project. Its server handles speech recognition and replies, so the chip only streams audio over Wi-Fi and animates the eyes.
His portable music player takes a different material route. It uses a CNC-machined aluminum body topped with a brass rotary knob. The player reads songs from a microSD card and outputs through a 3.5mm headphone jack. A Bluetooth mode lets the knob control a paired phone. Huy drafted the enclosure with SpeakCAD, an AI tool that generates 3D models from text descriptions.
Huy publishes materials lists and wiring diagrams for each build on his website, so every video works as a parts list and assembly guide. The watch’s project page hosts the materials list and the browser-based installer. The full build video is on HVT Lab.
Why owning the schematic matters
A solder joint you can see is a repair you can make. When you hold the schematic, the source code, and the hardware, no company can end support for your device by pulling a companion app or pushing a bad update. The brass esp32 smartwatch on your wrist then answers to you.
H/T yankodesign.com
Frequently asked questions
How much does it cost to build the brass ESP32 smartwatch?
According to Notebookcheck, the parts for the brass ESP32 smartwatch cost under $10 in total. The modder’s website lists every component with links so builders can order them.
What hardware is needed to build the brass ESP32 smartwatch?
The core parts are an ESP32-C3 Super Mini development board, a 1.3-inch OLED display, a three-way button, and a 3.7-volt battery. The battery charges through the board’s USB-C port.
Do I need coding skills to install the firmware on the smartwatch?
No, flashing the firmware requires no coding. It loads from Chrome or Edge over a USB cable, and the full source code is also available for anyone who wants to change it.
Can the brass ESP32 smartwatch show iPhone notifications?
Yes, the watch pulls iPhone notifications over Bluetooth. The firmware port adds this feature through Apple’s Notification Center Service.
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