I was building this shopping mall lately with this creator that said he'd conceived something that would become amazingly helpful in the future, and he was using some kind of 3 dimensional inkjet printer.
The basic plan was to dig this substantial hole in the middle of the desert, and then using some industrial three dimensional printing technology, we'd develop a retail center in the ground, and then put a condo intricate on top of it.
That way, people could come and move in to the apartments, and then go shopping down in the basement on the weekends, and view movies and eat pizza and stuff.
This way, it would generate the whole self-sustaining economy, and it would grow as people would make more people as we were trying to attract young families to move into our utopia.
Unfortunately, all of our wonderful plans were rapidly broken by some awful discovery that had been hidden underground for a few hundred years.
Apparently a race of cannibal zombies had grown hybrid tomato seeds hundreds of years ago, as they normally do on life-sustaining planets, with the notion being that when the population is big enough, it will eventually dig the hybrid tomato seeds out and they'll spring to living.