Not pinball, but in college we would take empty plastic bottle of soap and cut slugs the size of quarters. They would work great in the washing machines in the dorm. Another I remember when I was around 8-10 years old, The amusement park that I frequented had an arcade, that had skeeball for 10 cents. If when you pulled the lever back to release the balls, and released very slowly and carefully. The handle would not go all the way back, and you could just pull it again and again. Until you got caught.