Abstract: A toy assembles to provide a variably inclined trackway for rolling a ball or marble. The course of the trackway in both horizontal and vertical planes being variable by increments of fixed distances. A base has many vertical holes with modular spacing. Vertical members with lengths varying by a vertical length module fit in holes in the base. The horizontal path is chosen by selecting holes in the base. Horizontal elements with a right angle trackway segment on the upper surface fit on the vertical members. Elongate straight sloping elements with a straight trackway segment on the upper surface connect horizontal members on different levels to form a continuous trackway. Sloping elements are provided in different lengths for connecting horizontal elements that are different distances apart. The pathway can be configured for different slopes and crossing over and under itself without adjustment, special skills or tools and packs away in a small space. It may easily be made entirely of wood.