Abstract: The disclosure features systems, devices, and methods of sectioned compaction of composite materials for large parts. An example system includes a mold assembly, including a bottom wall, one or more side walls coupled to the bottom wall, one or more pistons, wherein the bottom wall, the one or more side walls, and the one or more pistons at least partially define a mold cavity, and wherein each of the one or more pistons are independently movable to reduce the volume of the mold cavity; and a plurality of fasteners configured to selectively immobilize the one or more pistons; and a compression actuator configured to sequentially advance the pistons from an initial position to an actuated position to compress a composite material within the mold cavity.