How thick do things need to be? Where does strength come from?
I think everyone should try this experiment... take a 8.5" x 11" sheet of paper, roll it (length wise) into a tube that is about 1.5" in diameter. With a single long piece of tape, tape down the outer edge of the paper to itself.
Now, stand it on end and put a 18 oz. cup of water on it.
Most people don't realize that you can substitute geometry for raw strength when building things. And solid thickness isn't better than something hollow in most cases. Why do builders use boxed frames or "I" beams rather than solid pieces of metal of the same thickness?
As it turns out, surface tension and geometry can be more important than the internal strength of a material (like the piece of paper in the experiment above).