Newtons Cradle - one of the classics from the 80's that is making a come back as a retro desk top stress reliever.
About the Cradle
The Newtons Cradle works as follows, if you pull one ball back and release it the energy is transmitted through the 3 static balls and the last ball then swings out then back again. If you pull two balls back and release them then the last two balls swing out, etc.
Confusingly addictive!
