The present disclosure provides methods, systems, devices, and kits for creating composite materials from a single resin, the composite materials having multiple continuous phases. The disclosure includes a process to three-dimensionally print objects (e.g., orthodontic appliances) with composite properties. In some aspects, the composite properties are formed from a single formulation with components that, when processed, have hard and soft continuous phases. In some aspects, the composite properties are formed by separately processing the hard phase components and the soft phase components. In some aspects, the composite materials and devices are three-dimensionally printed using the processed material.