I really like my F91W case with a Sensor Watch Pro board and accelerometer sensor.

My favorite features:

- Piezo alarm is much louder.

- Countdown time can be incremented by tapping the watch.

- LED color can be changed by adjusting RGB values.

- It features sunrise/-set and moon phase info/calendar.

- I changed the week day names to German abbreviations.

- There are lots of intriguing watch faces that you can compile into your firmware.

Sadly, the project is in some disarray as the originator apparently lost interest and the community isn't moving uniformly. Would love to see such a project for Casio with 4 buttons as this would allow for a lot more interesting use cases ... the pinnacle would be a board for their calculator watches. That would be rad.

The Sensor Watch forum on Discord is pretty active.

https://www.crowdsupply.com/oddly-specific-objects/sensor-wa...

There must be some significant creativity with limitations of the physical display layout! [1]

[1] https://www.crowdsupply.com/img/87bb/b84945f8-c8fd-4a06-9291...