This is a loose guide about how to create your own party house. We used a Sesame Street playhouse, but you can use whatever you have at home!
We put a roller switch under Cookie Monster's path, so when he comes home and rolls over it the party gets started.
To make the party atmosphere, we used 3 RGB LEDs (each turned to different colors), pulse modules (to create different blinking patterns), and a sound output to yell "surprise!"
While Mr. Hooper is dancing in the party, we set an alarm in his store for security. If someone opens his door, there is a light trigger that activates a vibration motor. The vibration motor is inside a bell that acts as an alarm.