True, there are quite a lot of those on sale, but I don't plan on recycling my conceptual craft. Aluminium seems viable for the roof, especially if I can get it to reflect some heat, even so, the roof would need to be in multiple parts to extend and retract (Even unfurl), thus not completely airtight, so heat is a problem. The roof would have to be light enough to lift, with enough insulation to stay warm, using electric linear shafts look like the way to go, Though they'll need power, especially if well insulated - Id have to downsize to about 20 feet which I'm not too upset about.