Share 'Kapoor/Isozaki : Ark Nova (Kangaroo 1or2 ?)'

Hello world ! I'm trying to model something like this really nice "balloon" structure from Anish Kapoor and Arata Isozaki: the Ark Nova in Matsushima. I understand it's an inflated structure and i'm sure it can be done with grasshopper... for now I've modeled some kind of cutted tore in rhino and smooth it with weaverbird but i'm not very happy with the result. How can i make something prettier…