Some people play with construction toys. Some people build massive and elaborate functioning structures out of construction toys. University of Colorado engineering student Andrew Locke fits into the latter category.
Locke built a fully functional pinball machine out of K'Nex. K'Nex may not have quite the same fame as Legos, but it's definitely a versatile construction system. It's also a very detailed construction system. It took Locke 4 months to put the beast together.
Locke didn't keep track of the exact number of K'Nex involved in his pinball, but he estimates it to be 17,000 pieces. About 4,000 of those are blue rods. I can't even fathom what it would cost to collect that many K'Nex pieces. The only non-K'Nex parts are rubber bands and the flippers.
The pinball acts a bit like a little roller coaster crossed with a Rube Goldberg machine. Chain lifts haul the ball up to good heights and let it go on winding tracks. Multiple balls can be in play at the same time.
In case you want to attempt your own working K'Nex pinball machine, Locke has kindly supplied instructions via Instructables. I know one thing. You're going to need a lot of K'Nex.(Via Reddit)