… and are time consuming to plan/organize, gather materials for, and build. Even if we all migrate to developed land (which, funnily enough, is supposed to be cheaper in the long run than getting raw land), there may not be enough building space for all the initial members. I have seen yurts used before and they are pretty neat. Environmentally friendly (no digging foundations necessary, made of simple materials), relatively cheap (to the tune of around 5k), and easy to build (basic one can be built within a week). Could be used as temporary housing until personal housing unit is built and then recycled as either extra unattached personal space (think office or meditation room) or donated for communal use (think halfway-house, spa enclosure, or guest room). For those of you out there, it also seems pretty easy to artsify.