Spinners are something to play with instead of clicking your pen or biting your fingernails. They are surprisingly addictive and sometimes help you concentrate.
The basic construction is a housing or holder with a bearing in the centre. To use it you just hold the spinner between a thumb and finger and spin it.
I decided to make a wooden spinner, which has a nice tactile feel and incorporate leds into it. The leds that I have used have a built-in program that changes the led colour fairly quickly, resulting in some interesting results when the spinner spins.