The Habitat Builder constructs your base: compartments, appliances, interior facilities (including the Fabricator) and external structures. A permanent home cannot be established without it, making it a foundational early unlock.
It is also a story tool: the Ancient Turbine repair requires the Habitat Builder loaded with 10× Mangalloy Ingots, 10× Strontium and 10× Titanium Ingots to restore the Karakorum Power Plant. The sequel’s base system is precision, piece-by-piece — see Base Building.