Is it possible to join 3 lines' nodes to make a 1 node corner without converting Outlines to Objects?

I recreated an  Ambihelical Hexnut ( http://mathworld.wolfram.com/images/eps-gif/AmbihelicalHexnut_600.gif ),
a Penrose Staircase ( http://mathworld.wolfram.com/images/eps-gif/PenroseStairway_700.gif ),
and a Penrose Triangle ( http://mathworld.wolfram.com/images/eps-gif/PenroseTriangle_500.gif ).

 Is it possible to join the 3 lines that make the illusion of a 3D corner, ie join 3 nodes to make a 1 node corner with 3 lines, without converting the Outlines to Objects?

Thanks!
Mulberi