it has certainly been done. you will need to understand, at least vescerially, the structural strengthes and weaknessess. also a LOT of cardboard, and a LOT of waterproofing coating materials, adhiesives, and so on.
Why would you build furniture out of cardboard? Scrap wood is easy to come by and you can build much better things with it from tools you can buy at the dollar store (well plus a handsaw). I've built many an Adirondack chair out of old pallets. If you get creative you can pick up shorter pieces of lumber and build shelves and tables. You just gotta get creative and you'll have better stuff that will last much longer.
Why do that. Watching the chairs collapse when someone was stupid enough to sit on them would all be part of the fun.