Apparatus and associated methods relate to using an additive (material deposition) process to incrementally form a closed-cell lattice structure formed as a unitary body in the shape of a marine hull cavity, the unit cells of the closed-cell lattice structure are substantially hollow. In an illustrative example, a method may include (a) forming a closed-cell lattice structure through additive manufacture, the hull cavity material may be bonded to an upper manufactured liner and a lower manufactured liner through lamination or mechanical connection. Unit cells of the closed-cell lattice structure may include hollow voids filled with gases. Providing the additive manufactured closed-cell lattice structure with a unitary body and hollow voids to trap gases may further advantageously promote the buoyancy and reduce the degeneration of a marine hull.