Honestly those 3d printed houses scare me, it basically turns houses into non-repairable junk that will have to be torn down the first pipe that bursts. Normally framed houses out of metal or wood are king for reparability that can be repaired for over a hundred years if not more.

The biggest obstacle to building houses in my opinion are entirely legislative/political. Towns oppose density and cause suburban sprawl galore which drives up costs of everything. Rich elites have also bought up land en-masse over the country so that even if you want to plop a house on a empty lot in a quaint town, they'll charge you half a million just to acquire the lot.