Trestle Tracks Builder SetProduct Description A truly mesmerizing marble track experience! Each set is made up of hollow stacking cubes and a variety of perfectly flat tracks. The paths cut out of each track widen almost imperceptibly from one end to the other, creating an invisible slope that propels the marbles forward. Watching them go is like magic in slow mo! Start with the 43 piece Starter set for an ideal introduction with three guided builds. Explore more with the 73