The propeller watches look so fresh and although you need a lot of battery power to continue over time, it is worth the cost. Making one seems like a very smart task, but actually it is quite easy to do if you spend some time in the instructables for one. You need a set of simple microcontroller LED and spinning motor to give the illusion of an analog or digital clock. The LEDs turn on and off with delay to match the speed of the rotating motor that is synchronized in such a way as to create a clock display hologram.
Following video is better to understand Propellerclock :