Discover Da Vinci's Workshop with three of NATIONAL GEOGRAPHIC's best-selling da Vinci's Invention Products. This kit includes 3 DIY building projects: Bombard, Catapult and Ballista. No special tools are required for you to build these three incredible inventions from Leonardo da Vinci. Everything is included in this kit: Laser-Cut Wooden Components, Rubber Bands, Sandpaper and clear, simple Instructions.