Ugears Marble Run Chain Hoist ★Mechanical 3D Puzzle Kit Model Toys Gift Present Birthday Xmas Christmas Kids AdultsModel size: 10. 6*12*10. 6 in (27. 5*30. 5*27 cm) Package size: 14. 9*6. 7*1. 3 in (37. 8*17*3. 4 cm) Number of components: 400 Estimated time of assembly: 7 hours Level: Advanced What is it about marble runs that makes them so compelling? Kids (and adults!) can watch marbles going down a track, passing through various obstacles, for hours on end. Marble runs are fascinating, they grab our attention, and yet they're also relaxing. Marble runs and