A solid free form fabrication (SFF) system and method is used to fabricate a three-dimensional structure in a continuous manner from successive layers of feedstock material. The system includes a gas shielding structure that is configured to protect a targeted region from oxidation. The system further includes a positioning arm coupled to the deposition head and moveable to align the deposition head with a targeted region of the three-dimensional structure and a plurality of control components coupled to the positioning arm for controlling a position of the positioning arm and operation of the deposition head. The gas shielding structure is formed as either a parallelepiped structure or a half disc structure and may be conformable to at least one surface of the three-dimensional structure.