Menger sponge revisited

Menger sponges (or cubes, whatever) are interesting objects.

The really interesting question is what the cross section looks like if you cut it in half.

No! not like that! Cut it in half perpendicular to a body diagonal!

Now try to imagine the outline and the inside outlines.....

Anyway. Menger cubes get complicated really, really quickly. Apparently openscad can handle a level two just fine, but level 3 is beyond the capacity of my computer. Oh well.