Cuboro is one of our favorites here at Oh! Toys.  Part marble run, part puzzle and part developmental and educational marvel, Cuboro is truly a "heritage toy" -- one which not only can be passed from one generation to the next, but which children will come back to time and again as they grow and become more sophisticated about their creations.   Cuboro Foundation Blocks:  Build bigger Cuboro creations but save the specialty blocks for creative purposes.  Visit Cuboro's home site in Switzerland for additional images and information.  Ages 3 and up.  CAUTION:  Marbles can represent a choking hazard to very young children.