3D printing functional materials, such as electronics, allows objects to be fabricated with both complex structures as well as functions. However, multi-material additive manufacturing continues to be a challenge in printing objects with different materials in controlled phases within a structure. For example, vat polymerization, including stereolithography (SLA) and digital light processing (DLP), uses UV/visible light to convert monomer resins to polymers via photopolymerization. Current approaches to incorporate multi-materials into 3D objects via vat polymerization include fillers that form composites throughout the structure or coating the polymer in an additional post-printing step. Here we demonstrate a strategy to create composites, gradients, and functional coatings using kinetics and thermodynamic miscibility to spatially control the placement of materials in one step within the object. With this method we can tune the conductivity of silver coated polymer structures and create 3D printed strain sensors and antennas.