Young thinkers can build unbelievable ball track structures with this simple stacking plank system. Create ramps, funnels, chutes and crazy contraptions like the "Black Hole" and "Bounce Plate." Then find out if the ball rolls as expected. Fostering unlimited creativity and experimentation, KEVA planks build an early understanding of proportion and balance, while teaching basic principles of physics and engineering. No glue, no connectors-just loads of constructive fun! Includes 200 identical wooden planks, 2 specially designed lightweight balls for maximum action and an 18-page idea book with project photos and quick-start instructions. Contraptions planks are made from pine.