Simple Rube Goldberg Machine with Some Dominos

This is a simple Rube Goldberg Machine with some objects interacting with each other. 

I built it with different basic geometric objects like cubes, spheres, and planes. In this demo, the machine is used to put a golden ball into a golden box

I found that objects that are not physically connected (i.e., having any joint parts) can still be considered as a rigid body. Another interesting fact is that large objects can have a really low mass such that a domino can push another domino that is way larger than itself