Metamaterial is engineered material with exotic properties not found in nature. We explore directed assembly and synthesis of optical metamaterials, including moire metamaterials and colloidal metamaterials, for various applications. Roll-to-roll manufacturing is being developed for the cost-effective large-scale implementation of moire metamaterials. We have invented a class of optothermal tools to assemble colloidal particles into metamaterials in an arbitrary and scalable manner. Inline multiscale metrology is applied to measure structures, dynamics and properties of metamaterials. We further explore particles and metamaterials coupled with functional molecules and atomically thin materials for active devices.