Beginner Arduino project! Looking for best sensor. Beer Pong Arcade!

I am very very new at Arduino programming and programming in general. But I was thinking of trying to build a computerized beer pong game. Something similar to this http://www.thisiswhyimbroke.com/beer-pong-arcade-machine but not as fancy. The first stumbling block while thinking it over was how to signal the Arduino when a ball goes through the cup (going to have bottom cut out and balls roll back).

I was thinking of a switch but that is not guaranteed to to trigger every time. My second guess was a “Ultrasonic Module HC-SR04 Distance Sensor for Arduino”

Any ideas or suggestions for the best sensor to use?

Thanks!

You could certainly do it with a distance sensor, but a microswitch that has an arm would be easier. You could also use a light/LED and a photoresistor.

I ended up using an led and a photocell on the other side. I measured analog input, and when it dropped below a certain value turns off led. Now to integrate a LCD display and speaker. Lots of work ahead of me!

How many cups are you setting up?