Contraptions are ramps and chutes, tracks and towers, funnels and more simply by stacking KEVA planks. No glue or connectors are used, just gravity and imagination. The two specially-designed KEVA balls provide bouncy action and surprising moves. Make the ball roll, twist, bump, bounce hop and stop through your contraption. The contraption guidebook is loaded with dozens of full colour photos, tips and instructions to build numerous clever contraptions. Planks are made of pine.