As additive manufacturing evolves, increased capability is desired. Capability to build multi-material parts at near-net shape allows greater design freedom by increasing mechanical and performance properties while reducing weight and lead-time. Ability to scale manufacturing to large components is difficult with traditional methods. A new solid-state additive manufacturing process, Additive Friction Stir (AFS) both increases the types of materials that can be used for production and increases scale of production. In this work, AFS was used to fabricate a variety of metal matrix composites, demonstrating flexibility of material combinations. Layered material combinations were created to produce metallurgically bonded multi-material products. Results from a study of microstructure, interfaces, and mechanical properties for material combinations, MMCs, and gradient structures including Al, Cu, Mo, Fe, Ta, R, SiC, steel, and nickel based alloys will be presented. Limits and opportunities of the process for fabrication of large components will be reviewed.