Without people, there's no need to build a city. I want to build it here in Portland, OR, USA, in part because I think it's a nice place, and in part because I think it would address most of the problems the city is currently dealing with.
Anybody in or willing to move to Portland to make such a thing happen? If not, does anybody have an alternate location they can make a good case for?
Cultural structure is much trickier than economics; it suffers from more of the 'false expert' syndrome. I'm willing to take notes on that discussion, provided we agree in advance that nobody anywhere has written a full explanation to the topic and what we're trying to do is generate the content from which to work.
Economics is a tricky subject; I know just enough about it to know that we don't know enough about it. We need resources to create a city, and those resources, however artistically and efficiently we use them, have to come from someplace. Beyond that, we need to ensure that on an ongoing basis, enough resources flow into the city to keep it running, and that we have a way of disposing of excess resources before they reach toxic levels.
Sunbeam City is a Libertarian Socialist solarpunk instance. It is ran democratically by a cooperative of like-minded individuals.