in “Trus no one” I did research of the use of cardboard carpet-rolls in structures.
As a starting point I made a set of 3; a beam, a connector and a knee. With these 3 parts in a bigger amount, virtually any structure can be made.
To make these parts I had to build a pipe notcher big enough to handle the 120mm cardboard pipes.
The parts are strong (and heavy), but it’s hard to say to what amount they can be trusted.