I made a small Rube Goldberg machine using pressure sensor and servo motor. I needed something that had movement so I bought two kinds of DC Motor and also a Motor shield kit. But it was still not easy to do and I changed to servo motor. For pressure sensor, I just wanted to try it and chose two kinds of sensor to play with.
1. Press pressure sensor
2. When the servo motor pushes the blue car forward, the blue toy starts to shake its arms and feet
3. Small blue car knocks down the wood piece