Modern nanochemistry has developed efficient techniques to manipulate nanoscale objects with a highly advanced degree of control. Chemically- engineered nanoparticles can be synthesized with a large choice of sizes, shapes, constituent materials and surface coatings, and further assembled spatially into self-assembled structures, either spontaneously or in a directed manner . Advances in particle self-assembly and the quasi unlimited range of nanostructures with controlled architectures and functions available suggest that such assemblies may also provide a simple route to metamaterials at infrared and visible length scales. Indeed, nanochemistry and self-assembly strategies are able to inexpensively produce materials whose inner structure is natively in the right range of sizes for optical and infrared applications and can provide fully three-dimensional (3D) structures, thus opening the way to the fabrication of 3D-metamaterial samples of finite volume of the highest importance to many applications. Such metamaterials may be used, for example, to create 3D homogeneous, isotropic negative index materials (NIMs), with simultaneously negative permittivity and magnetic permeability, cloaking devices or light-based circuits manipulating local optical electric fields rather than the flow of electrons. © 2010 IEEE.