Pardon the double entendre....
If you would be so kind, would you take a gander at the "Grand Central" table at this link and fathom a guess as to what the hinges are made from--assuming they're all made from the same thing.
It almost strikes me as some scored plastic somehow glued on to the pieces.
By the way, for the math gifted, I think the largest you can make the 4 equidistant folds in the table, and still have it fold correctly is around half the distance of the table's radius when fully extended--but I can't prove that yet and I would love someone to suggest otherwise with rationale to back such a claim up.
Oh--and I'm thinking that in theory, this could be done with inset piano or butler hinges. Tell me what you think about that.