If one box of K'NEX can make a single loop coaster, can I make a Double Loop with two boxes? Yes, but it took many designs and lots of trial and error to get the car to stay on the track! (Unlike real coasters, these cars are not locked to the track.)
In this picture, one car is on the lift hill while the second car enters the bottom loop.
I used nearly 2,000 pieces to build this coaster. It took several days of work until it operated properly.
©2009 Joel A. Rogers.