The use of composite materials for 3D printing is a promising area of study that is largely under-researched. Traditionally manufactured composites are known to have superior mechanical qualities, yet characteristics of 3D printed composite materials are not well documented. In this study, polylactic acid composite filaments with both bronze and stainless-steel reinforcements were characterized using optical microscopy, X-ray powder diffraction, energy dispersive X-ray spectrometry, scanning electron microscope, and nanoindentation to determine reinforcement concentration and elemental composition of the filaments. Samples of each composite were printed with a fused deposition modeling 3D printer for compression and tensile testing in accordance with ASTM standards. Specimens with varying print patterns, build directions, and layer heights were tested to determine the efficacy of each material reinforcement and the effect these user-defined parameters have on the overall mechanical characteristics of the composite. Samples were subjected to 500 hours of accelerated weathering according to ASTM standards. Degradation was due largely to the ultraviolet exposure of the test, and the metallic reinforcements showed reduced crystallinity and resistance to physical deformation. This research provides the Navy and Department of Defense with qualitative data to determine the applicably of 3D printed parts for use in structural and load-bearing components onboard submarines.