A strong wrapping paper tube and a ball of some sort (we used a jingle bell). That's all this quickly invented idea requires!
I cut the tube into two different sizes, grabbed one of Tyler's favorite jingle bell ornaments from his tree and demonstrated how to put the bell into one end of the tube and how the bell will come out the other. Though the movement itself wasn't difficult, he found this quite interesting, repeating the action over and over again.
I then provided a different sized tube, about half the size of the first, and he experimented again. For some reason, the bell became stuck a few times in the smaller tube, but he soon learned to shake the tube in order for the bell to roll out.