I Am Sure We Have All Seen,

Fidget Spinners,

take a slanted table, some pieces of wood, a few pencils and a number of fidget spinners with the mind of Kaplamino,

who is a talented toy builder and you get this chain reaction, for more of his marble runs have a look here, as an aside the blue marble run at this link was the culmination of 3 months work and 500 fails!