How about taking the best of both worlds? Move the printer relatively nearby (it could be on a boat, for instance), and have it print prefab items on demand; th

How about taking the best of both worlds? Move the printer relatively nearby (it could be on a boat, for instance), and have it print prefab items on demand; those can have complex and one-off shapes as well. You likely make it cheaper by using locally-sourced materials (gravel, sand, cement if possible) instead of transporting those. And you can probably pack the rest a lot more tightly than moving those air-filled walls around.