“Face touch” vibrating notifications with a sub $10 SmartBand: https://media.mit.edu/projects/saving-face
A sub $10 fitness tracker as wearable development platform!?
For this cost, this smart band has a looot of features:
To get it, you can try these links:
If they’re broken, this list should help to find more.
To customize the firmware, just clone this repo, and compile the code with this adapted Arduino library environment.
The following links should help understand the pinout:
Bonus: ATC1441 made this great video to explain how the firmware upload works (among other things).