Placing. Pick a building in the construction panel and click the map: it is paid for at once and its site goes down. A building must stand within 3 tiles of one of your others, as in RA2. The ground that qualifies is tinted turquoise while a building is in hand. Walls count only for more walls. The MCV can deploy anywhere, to start a base far from your first.
Drones. A site needs at least 4 drones working on it to print at all. The Fabricator Core starts with 4, so at first it prints one building at a time. Upgrade it (select the Core, press R) for 4 more drones a level, up to 48. Each level costs more than the last and takes 8 s to fit. With more drones you print several buildings at once, and more drones on one building print it faster, up to 24 on a site.
Drones can be shot down on the way or at work; the Core builds replacements, one at a time, at 75 Sunresin and 3 s each. Give a site priority (R) to send drones there first.
Walls. With a wall in hand, click in line with your walls and the gap fills itself, up to 12 segments at once; or drag a line of its own. The wall stays in hand for the next run.
Power. The Fabricator Core and every Energy Core supply power; everything else draws it. When demand outruns supply, production and printing slow in proportion (down to 25%), Pulse Turrets fall silent and the radar goes dark.
Repair and sell. Select a building to repair it (paid as it goes, W) or sell it (L, twice) for 50% of its worth, less for damage. Engineers repair buildings and vehicles for free.