A method of manufacturing a multi-sided or otherwise relatively three-dimensional formed structure for, e.g., an aerospace vehicle. A relatively planar base structure is constructed using a first construction technique. Features (e.g., ribs) are incorporated into the base structure using a second construction technique (e.g., additive or subtractive manufacturing) to create an intermediate structure. The intermediate structure is folded along fold-lines or otherwise physically formed to create the formed structure, such that some of the features are located within an internal space defined by the formed structure. Joints between the sides of the formed structure are welded, fastened, or otherwise secured. Separately constructed additional elements (e.g., bulkheads) may be incorporated into the structure. A closeout element may be added to the formed structure to further define and close the internal space. Throughout the process, the structures, features, and elements may be refined to desired tolerances.