cube([15,85,60]);
translate([15,15,0]) cube([42,55,15]);
polyhedron(
    points=[ [15,35,15],[54,35,15],[15,35,57],
               [15,48,15],[54,48,15],[15,48,57] ],
    triangles=[ [0,1,2],[0,3,5,2],[3,4,5],[0,1,4,3],[1,4,5,2] ]);