Talk to UP Greg, he machines trichotometric indicators and rectabular brackets all the time at work.
I think his i-beams were made using cutting edge rectabular technology aslo. Mcfadden-Dale hardware might have the ambihelical nuts in stock.
Here's the cool thing about Escher prints, they're mostly linoleum block prints. Meaning he carved out the linoleum that he didn't want to print b4 stamping the block on an ink pad and then on a piece of paper. That means he had to visualize the whole thing sort of backwards and then carve it that way.
"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
The two "big" triangle images (top and bottom) aren't really triangles. The line along the edge of the top isn't a straight line. On the top image, the line angles up slightly at the point where the red triangle meets the green triangle. On the bottom image it's the opposite, it anles down...the green triangle has a steeper face. That means there's more volume in the lower view, where the green triangle is first, leaving room for the empty square. Kinda hard to explain, but once you look at it again, It's pretty clear.
Damn...I should be out working on my truck but i'm in here reading this stuff. I've got to get my priorities straightened out. Alright, one more beer, then I go out in the garage......
That wasnt too hard figure out you can tell that the different arrangement caused the top line to cut higher thru the box graph making space for the empty area. As for the print outs overlapping perfectly , I dont believe that is possibly the lower triangle will be a slight bit higher all the way from bottom to top. It just isnt that noticeable unless you are looking for it. amI right?