Seems you can yet make easily planar forms :)
Then make Shell

So possibility to intersect with your perpendicular plexiglass rectangles

But I don't very well understand what must be the final result?
A ropes skull?
Have you an example of such thing?



PS With the Browser does it possible to select only open curves (after the planar automatic function)
On the drawing above there are some open curves (for close it manually or with other method)

And there is not inverse selection inside the Browser? (Because I have found how see only the surface :)