The "bottom" and "top" pieces have the same length (transversal in your projection), as the 3d figure shows. But if you try to place the pieces so that their ed

The "bottom" and "top" pieces have the same length (transversal in your projection), as the 3d figure shows. But if you try to place the pieces so that their edges match on a projection, then they cannot start and end at the same point (one is "nearer" the camera than the other).