Well every house I mean. Every house can be completely custom. I said "item" because the same goes for every type of 3D printing.

This is the big advantage of 3D printing over a standard manufacturing line. If you're going to print out 1000 or more of the same things, there is really no point in 3D printing. Regular methods are more efficient (e.g. prefab when it comes to construction, injection molding when it comes to plastics). The benefit of a 3D printer is that it can make different things each time, not the same thing every single time.

If I were to get a house 3D printed I'd design it really organic, Gaudi-style.