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BUILD YOUR OWN E-PAPER SMARTWATCH FOR 60 DOLLARS — THE BATTERY LASTS A WEEK

A smartwatch that arrives as loose parts, runs Arduino code, and sips so little power it lasts a week.

by SQFMI

FULL CAD BOM FIRMWARE DOCS

Open-hardwareDisplays

Built withESP32Arduino3D printing

difficulty
●●●○○
time
an evening
license
MIT
repo
repo ACTIVE2,848 stars

WHAT YOU’LL NEED

Videos
1
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COMPAREE VERDICT

Watchy is an open-source e-paper smartwatch you assemble yourself: an ESP32 with Wi-Fi and Bluetooth, a 200x200 e-paper display that holds its image without power, an accelerometer, a vibration motor and a real-time clock, in a printed or aluminium case. It ships with working firmware, and the Arduino library and example faces (with prebuilt binaries) let you change everything; the community has built many more faces. The catch is that customising means Arduino IDE: install the ESP32 core and the Watchy library, pick or write a face, and flash it. SQFMI quotes 5 to 7 days of battery for timekeeping and 2 to 3 days for faces that fetch weather over Wi-Fi. The thing most likely to go wrong is the glass display: it cracks if bent, so follow the assembly guide carefully. If you want a watch you can program yourself and never wonder what closed firmware is doing, this is it. If you want phone notifications and apps out of the box, buy a finished smartwatch.

GOOD TO KNOW

  • —MIT-licensed hardware and software; commercial use allowed.
  • —The Arduino library and watch faces are in the main repository; PCB files and case models live in SQFMI's separate watchy-hardware and watchy-cases repositories.
  • —Battery life is 5 to 7 days for timekeeping only and 2 to 3 days if the face fetches data over Wi-Fi, per SQFMI.
  • —The separate watchy-hardware repository has a component list (designators, footprints and values) but no supplier part numbers; the assembled kit is sold through Mouser, The Pi Hut and Crowd Supply.
  • —Dozens of community watch faces exist, but you have to compile and flash each one yourself.
  • —Watchy ships with working firmware pre-loaded; trying other faces means compiling and flashing them in Arduino IDE over USB.

Parts to buy

2 items

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

  • Watchy kit from MouserFind
  • Pi Hut or Crowd SupplyFind

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Can I build this?

PrintOne case: back shell, front bezel, and strap clips. PLA is fine; PETG if you want flex in the strap.
BuyThe Watchy kit from Mouser, The Pi Hut or Crowd Supply (case and accessories from the SQFMI shop), or source the parts from the open hardware files.
ToolsSoldering iron for the through-hole battery connector and vibration motor if you buy the bare board; USB-C cable; Arduino IDE; wire strippers if you are routing your own battery lead.
SkillsNo soldering for the kit: careful handling of the glass display and its ribbon connector, then Arduino IDE skills if you want to change faces.
TimeAn evening: under an hour to connect the display and battery and close the case, then another hour or two picking a face, compiling it, flashing it, and realising the time zone is wrong.
CostMid band: the kit is about 59 dollars plus shipping on Crowd Supply and already includes a case; a printed or aluminium case is optional. If you source components separately you will not save money unless you already have the e-paper display.
SafetyNo real hazards. The LiPo is small and has a protection circuit; the watch runs at 3.7V. Ordinary care around a soldering iron and a live USB port.

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

Videos

This DIY Open Source E-Paper Smart Watch Is The Coolest! Watchy

SQFMI's getting-started guide links official assembly videos for the standard and aluminium cases; this hands-on review from ETA PRIME shows the finished watch in use.

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Gallery

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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. 1.Order the Watchy kit from SQFMI or collect the components from the BOM in the repo. (The kit includes the board, display, battery and an injection-moulded case. If you want to source parts yourself, the component list (designators, footprints, values, no supplier part numbers) is in SQFMI's watchy-hardware repository.)
  2. 2.Print a case from SQFMI's watchy-cases repository, or buy one from the SQFMI shop. (PLA works; PETG gives you a little more flex in the strap clips.)
  3. 3.Install the Watchy Arduino library and pick a watch face from the examples folder. (Each face is a separate sketch. The repo includes a default face; the community has made dozens more.)
  4. 4.Compile and flash the face over USB, then assemble the watch into the printed case.(The Arduino library handles the RTC, e-paper refresh, and Bluetooth pairing. You just set your time zone and upload.)

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

  • Battery life depends on the face: SQFMI quotes 5 to 7 days for timekeeping only and 2 to 3 days for faces that fetch data over Wi-Fi. Turning radios off and updating less often extends it.
  • Changing faces means building or flashing firmware: there is no app store or graphical face editor, though the examples include prebuilt binaries.
  • E-paper refreshes slowly — a full screen update takes a second. If you expect instant notification pop-ups, you will be disappointed.
  • The case design assumes you are printing with supports on; if your printer struggles with overhangs, the strap clips will sag.
  • Time zone and NTP settings are hard-coded in each sketch. If you travel or change faces often, you will be editing and reflashing regularly.
  • The Arduino library is well-documented, but if you have never used PlatformIO or the ESP32 board manager, expect an hour of setup before you compile anything.

Can I use this with an iPhone?

The official firmware does not offer phone notifications; watch faces use Wi-Fi for things like weather and time sync. Any phone integration would come from community firmware or your own code.

How do I add a new watch face?

Find a face in the examples folder or on GitHub, open it in Arduino IDE, set your Wi-Fi credentials and time zone, compile, and flash over USB. Every face is a separate firmware image.

Can I run MicroPython or CircuitPython instead of Arduino?

Not officially. The Watchy library is Arduino-only. You could port it, but you would be on your own.

What happens if the battery dies completely?

Recharge it over USB, then set the time again; faces that sync over Wi-Fi can fetch the time automatically.

Is the display always on?

Yes. E-paper holds an image without power, so the watch face stays visible even when the ESP32 is asleep. That is why the battery lasts a week.

Community builds

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

Discussion1

FROM THE COMPAREE TEAM

The e-paper display holds an image without power, so the watch face stays visible for a week on a charge — but every refresh takes a full second. Would that latency bother you, or is a week of battery worth the wait?

CompareeTEAM2mo agoedited

Practical notes from our verification: the main repository holds the Arduino library and example watch faces (with prebuilt .bin files), while the PCB and case models live in separate SQFMI repositories. Watchy ships with working firmware pre-loaded, and the official getting-started guide covers assembly (with SQFMI's own assembly videos for the standard and aluminium cases) and Arduino setup. Handle the glass display carefully: it cracks if bent, and the guide warns not to force the case closed or overtighten the aluminium case screws. SQFMI quotes 5 to 7 days of battery for timekeeping only and 2 to 3 days for faces that fetch data over Wi-Fi. Watchy is sold through Mouser, The Pi Hut and Crowd Supply, with cases and accessories in the SQFMI shop. 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.

SQFMI

SQFMI is a small hardware studio that builds open-source e-paper devices. Watchy started as an experiment in how much smartwatch you could fit into an ESP32 module and a 1.54-inch display, and the answer turned out to be 'enough that people keep buying them'. The hardware has been stable since version 2.0.

GitHub

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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.
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