Unfortunately, those building 3D printers are mostly just a publicity stunt currently. Too impractical to use at any sort of scale.

Now, if we were to combine AI with the old Sears kit homes, we might be onto something. Given a standardized list of stuff like room dimensions and the materials required for their construction, AI could probably generate an endless number of variations of both houses and additions for them with an exact list of required construction materials and equipment. Entire series of standardized houses with all the materials prepped ahead of time, ready to just be delivered to a plot of land and constructed on site by a local construction companies, with only minor adjustments required to account for the specific peculiarities of the area. The IKEA of house construction.