The Casio F-91W has maintained its status as an affordable, reliable timepiece for decades, beloved by everyone from students to presidents for its simple functionality and retro charm. Yet in an age of smartwatches and fitness trackers, many users find themselves torn between nostalgia for classic design and the convenience of modern features.
What makes the Ollee Watch particularly compelling is how it bridges this gap without compromise. This open-source project transforms the iconic F-91W into a customizable, connected smartwatch through a clever mainboard swap, preserving everything people love about the original while adding the smart features they actually want.
Designer: Ollee Watch
The upgrade process centers around replacing the F-91W’s original circuit board with a custom-designed PCB packed with modern sensors and Bluetooth connectivity. You keep the lightweight resin case, the classic LCD display, and even the water resistance, but gain step tracking, smartphone notifications, and customizable features. The installation requires basic disassembly skills, making it accessible to most DIY enthusiasts.
Of course, the real appeal lies in what the new mainboard enables. The Ollee Watch adds a step counter with daily goals and vibration alerts, Bluetooth syncing for automatic time updates, and customizable alarms that go far beyond the original’s basic functionality. World time zones become easily accessible, and the companion app lets you configure everything from your smartphone.
The open-source firmware opens up even more possibilities. Community developers have already created mini-games like Blackjack, custom watch faces, and additional features that expand the watch’s capabilities over time. You get a device that can evolve and improve through community contributions, something traditional smartwatches rarely offer.
That said, the user experience remains refreshingly familiar. The Ollee Watch looks and feels exactly like a classic F-91W, maintaining the lightweight comfort and discreet profile that made the original so popular. The rechargeable battery provides days of use per charge, while the retro aesthetic means it works with any outfit or occasion.
The affordability factor makes this particularly attractive. You can transform a $20 watch into a feature-rich smartwatch for a fraction of what most connected devices cost. This approach appeals to both nostalgia enthusiasts who love the F-91W’s classic design and tech-savvy users who want modern functionality without the bulk or expense of traditional smartwatches.
You’ll notice how the Ollee Watch embodies sustainable design principles by giving new life to existing hardware rather than creating entirely new products. This upcycling approach reduces waste while celebrating the enduring design excellence of the original Casio.
The Ollee Watch taps into something fundamental about how we relate to our favorite gadgets. You can see how a simple mainboard swap transforms a $20 classic into something that feels both familiar and surprisingly capable. This kind of thoughtful upgrading respects what people already love while giving them exactly what they didn’t know they wanted.
