Looking forward to the day when you can just deploy an army of mini robots that 3d print their way along building the hull as they go.
It would be easier to build them on earth still.
Instead, you'd ship a lump of whatever material is required by your printer, and manufacture whatever is needed, on demand.
It's more compact and more versatile, what's not to like? Weight is at a premium when you are talking about payloads, but so is space.