We explore directed assembly of optical metamaterials that offer new ways of manipulating electromagnetic wave. These include moire metamaterials and metamaterials with colloidal particles as building blocks. We develop optothermal manipulation techniques to assemble colloidal particles into desired configurations in a scalable manner. Inline optical metrology is applied to measure structures, dynamics and properties of metamaterials at single-particle resolution. We further explore colloidal particles coupled to molecules and 2D materials for active metamaterials, devices and tools.