Video: https://drive.google.com/file/d/0Bxu-j9eOkv5XcHVCQUZIdVJERFE/view?usp=sharing
I created a switch that when you put your mug on the coaster, then the LED will light on. I used conductive tape on the top of the coaster and the bottom of the mug. The bottom of the mug is connected to the positive side. And the top of the coaster is connected to the negative side.
