Meet the Flux Chair: a folding chair that looks like an envelope but unfolds to become a strong chair capable of supporting up to 353lbs of weight. The chair weighs only 11 lbs and is made of sustainable polypropylene. When you are done with it, simply fold it to get it out of your way.
The above video should give you a better idea how this folding chair works. You get a bunch of color options to choose from. Not super cheap though.