So you would like to develop your own smart wearables? The watchX platform can help. It is a smartwatch compatible with Arduino and Scratch, so you can program it to perform a variety of tasks. Advanced users can use Atmel Studio to do more with the watch. Its case can also be 3D printed.
You can use watchX to play games, track fitness activities, and do a whole lot more. It has a 1.3″ OLED display, real-time clock, accelerometer/gyroscope, temp & barometric sensors, and Bluetooth.