[szemet]

DIY? Found this: https://github.com/carrotIndustries/pluto

But they've made different design decision:

Q: Why is there no accelerometer? A: Accelerometers are the most useful when they're permanently active for applications like sleep trackers, pedometers or features like "shake to do something". Unfortunately, even accelerometers marketed as "ultralow power" draw approx 30 µA when running, draining the CR2016 coin cell in less than half a year. So we decided to dedicate the available space to a digital compass.