The Arduino watch was a bit too big and it was difficult to attach the screen to the processor. So I have started to build watches with the 4D systems microOLED-96-G1.
The watch has 2 rechargeable 3.7 V 400mA batteries in parallel. They last about 36 hours with the screen occasionally on. The batteries are inside of the band and they can recharge within the watch.
It has a button for turning the screen on.
Software shows present time/date as well as the time in 4 time zones (Japan/Korea, California, New York, England).
By pressing the button twice quickly, you can change modes to adjust the time or change the alarm time.
Also includes small speaker for alarm (GOLDELOX can produced sound) and button press turns off alarm.
Here is the most recent version, with the thinnest profile.
Here is an older version
An earlier version
Yet another version