Dive into the world of mechanical engineering with this fascinating 3D marble run from wooden city. The set creates fascinating effects with steep downhill slopes, sharp turns and a funnel track. Continues operation is ensured by a hand-operated elevator, the launched metal balls pass all obstacles on different trails and rise again to the top. Including 12 metal balls that move one after the other. Made from eco-friendly birch plywood No Glue required to assemble Assembled model size: 10.94" x 6.5" x 7.72" Model size in a package: 6.89" x 9.45" x 1.10" Number of parts: 259 Operating time: 1 Minute Approximate time to assemble: 5 Hours Not Recommend for children under 14.