This angular, helium-filled balloon was produced for atrium of the Museum of Contemporary Art in Tokyo by Junya Ishigami (who is too cool to have a website), for an exhibition entitled Space for Your Future. It uses an aluminium truss frame and thin reflective alumnium panels (they look almost like foil, but I think they are a bit thicker than that). Apparently it weighs about a ton! Images are from Japan Architect 72. A couple of flickr images here.