Earlier quoted context omitted.
In some potential future, there is an engineered a plant/fungus in a pot that you place onto the worksite. Months later, with regular sugar-water and hormones, it gives you a root-pipe for pennies a day. Of course at that point we might not need the cheap pipe in the first place.
Nanobots that manage a plant / fungus / bacteria/‘ / amoeba workforce. They drill and line boreholes to both anchor the foundations of the building and provide a closed loop system for a reticulated-water ground-sourced heat pump system. They also use the soil recovered from the boreholes to build the soil-polymer foundation. In the future, pallets of nutrient-cement are placed on the site and the bio-borg-bot farm a…
That reminds me of a less grey-goo-adjacent idea from a Larry Niven book, in which the base-structure of houses were cheaply made by growing a kind of coral inside a watertight scaffolding.
Given the last few centuries of humans under-estimating nature, I predict that many "nanobots" predictions will turn out to be a kind of optimistic hubris. We'll end up making comparatively minor tweaks to the massive base of existing nanobots called biological life. Especially the multicellular varieties, which have many tested and integrated strategies for building things, such as the towering bipedal mega-fortress my hive mind currently inhabits.