In about the time it took to replace the roof over my head eight years ago, thanks to the wonder of 3D printing:
They’re larger than many shacks in most shanty towns; and, for a large family, it would be no problem to build two of them side-by-side. As for utilities and services, that’s a much larger job, and probably more expensive than the houses themselves; but given affordable housing costs, that’s not an insoluble problem. Best of all, being built of cement, these are likely to be relatively safe against wind and weather, even hurricanes or nearby tornadoes. The roof may go, of course, but that can be mounted with stronger bracing to keep it attached except in the worst conditions.
Two of them side-by-side might run $10,000 — for over a thousand square feet, or about the size of my house, which is believed by some to be worth around a hundred grand. It’s probably not the most viable idea in a city this size with lots of old housing stock just begging for reuse; but think “shanty towns,” or a Third World without them.