You'll never tire of watching steel balls race through this elaborate system of starts and stops, twists and turns. Build it with your own hands, crank the handle, and see it go into action as balls accelerate down spiral slopes, move through small switches, pass through a swinging ball separator, zoom down a S-shaped transparent orbit, ride a lifter, and more. Punch out the laser-cut plywood pieces and follow the step-by-step instructions. Wood and acrylic, 294 pieces, 10 steel balls. Finished size 8½"w x 13"h x 9"d. Ages 14 and up.