cube([66,66,20]);
polyhedron(
    points=[ [0,0,20],[0,19,20],[66,0,20],[66,19,20],
               [0,0,50],[0,12,50],[66,0,50],[66,12,50] ],
    triangles=[ [0,1,3,2],[4,5,7,6],[0,1,5,4],[2,3,7,6],
                 [1,5,7,3],[0,4,6,2] ]);
polyhedron(
    points=[ [0,66,20],[0,47,20],[66,66,20],[66,47,20],
               [0,66,50],[0,54,50],[66,66,30],[66,49.33,30] ],
    triangles=[ [0,1,3,2],[4,5,7,6],[0,1,5,4],[2,3,7,6],
                 [1,5,7,3],[0,4,6,2] ]);