At Paradigm, we are positively passionate about puzzles. Kids of all ages love our 3-D puzzles (and we mean adults too)! Build your own intricate system of cogs, gears, and wheels, and watch marbles racing down slides full of crazy twists and turns! Full of elaborate mechanisms and small tricks. The precise gear design provides a smooth transmission speed ratio. You can also learn the fundamentals of engineering and the structures of machines. The puzzle has a stair stepper as an elevator, a spiral funnel, 2 straight rails, 3 curve rails, a wheel lifter to bring marbles to the top, a flip-flop as a switch to drive marbles to, and a hand crank to make the whole system move. No glue, tape, or tools required. Finished size 17" x 2.4" x 3.6". For ages 14 and up.