I would imagine that the vast majority of those who have studied design have faced the challenge of designing a seat from cardboard. I still come across photos of my efforts from first year and while it's not up to standard to post on here, I do think that it could be in interesting starting point from which to refine.
I have seen some really interesting solutions in the past but when I saw this one over at
Wilson Brothers I was struck by the simplicity and elegance of the structure.
Also in Alubond or similar: