This project uses two 555 timer IC's to generate a ball that ricochets in the X, Y, and Z directions, as if comes from within the oscilloscope, bounces off of the inside glass and sides, and back into the oscilloscope!
Each 555 timer is generating a triangle wave with different frequencies which connect to the two oscilloscope channels using X-Y mode. Because the two waves are out of phase it appears that the ball moves around the screen in a random manner. The oscilloscope Z-channel is also connected to a function generator which makes the ball gradually turn on and off.
The oscilloscope's point of light was widened into a ball by turning the oscilloscope's focus to maximum. Both 555 timer ICs are run from a 9V supply.