As someone who isn't in the industry, that raises the question - is framing usually the choke-point? They say it took half the time, so is that other half the time all framing? Or is there other factors at play here?
I'd say the choke point are the various trades (electrical, drywall, plumbing, siding, painting, roofing, irrigation, windows, inspections, etc.) doing their thing, which can take months.
The total time of 2 months seems very optimistic to me.
Wouldn't you wait for the 3d printer, the operators of the 3d printer and the material to be printed out just the same?
But you won’t own the machine for the same reason you don’t own a cement truck. It would be not economical to do so. And even if you would own it you have no clue how to operate it and it would not be economical for you to learn.
Just think about the consistency of the material it is extruding. If it is too runny the walls will sag. If it is too solid the material will jam the pump. Or think about the work of cleaning the pipes after work so the concrete doesn’t set in them. These are all solved problems of course, but if you are not a contractor specialising on this equipment you will just make a mess and likely ruin both the printer and the house being built.
So what will you do? You will contract the job to a specialist. Someone who knows how to operate the printer and has one to work with. What are the forces that will make that contractor any better than the ones already existing? This machine will also require employees and materials be on time. Won’t the same problems of “one man bands that fail at every corner” show up with this type of contractor too?