Quercetti 45-Piece Transparent Marble Run - Marble Run Construction Toy
What goes up must come down! With the Transparent Marble Run,  kids will erect tubes, chutes, bridges, and spinning wheels and send  nine swirled marbles one after another through the structure, all the  while learning some simple principles of physics. Many designs are  possible with the transparent and pliable blue, yellow, and pink tubes.  The enclosed marbles can't jump the track and, at the end of the run,  they come to rest neatly in a tray. When playtime is over, all the  pieces fit in a durable plastic box.--Lynne Sampson