Young thinkers can build unbelievable ball track structures with this simple stacking plank set. Create ramps, funnels, chutes and crazy contraptions like the “Black Hole” and “Bounce Plate.” Then find out if the ball rolls as expected. No glue, no connectors: just loads of constructive fun!Includes:KEVA Contraptions 400-piece plank set comes with 400 wooden planks, 2 specially-designed lightweight balls for maximum action, a canvas zippered storage bag and an 18-page idea book with project photos and quick-start instructions. FREE Bonus Planks set includes 50 extra KEVA planks for even more building!• Basic building planks can be used to build endless configurations• Fosters creativity, experimentation and STEM education• Builds an early understanding of proportion, balance and basics of physics and engineering• Planks are made from solid, unfinished pine and easily store within the included canvas bag