As a kid I was fascinated by those big Casio watches crammed with sensors. The fascination never went away and is now combined with the DIY electronics skills I have picked up over the years.
The Open-Smartwatch is about providing electronics modules, 3D printed cases, and an operating system to build your own smartwatch, either pre-assembled or from scratch. Currently, there is a hardware module, called the light edition, to build a watch with a 1.2inch 16bit TFT screen. The open-source toolchain using PlatformIO and the Arduino framework, allows you to write your own apps and watch faces or chose from the existing examples to develop tools and games.
I learned a lot about designing energy-efficient PCBs for tiny devices. A watch does not leave much space for components and aiming for a slim design is a challenge and requires the selection of the right ICs. Improving the hardware required to make the OS modular to adapt it to the changing hardware configurations.
The Open Smartwatch has turned into a community project with dozens of contributors and makers around the world contributing code or developing further hardware revisions to adapt the project to their tastes.