One embodiment of a method for producing a plurality of nanostructures embedded in a host comprising the steps of: assembling a first preform, drawing said first preform into a first fiber, cutting said first fiber into a plurality of pieces, assembling said pieces of said first fiber into a second preform, and drawing said second preform into a second fiber. The host is made of a low thermal conductivity material such as a polymer or combination of polymers. The host can assume the form of a plurality of nanotubes which further reduces the host's thermal conductivity due to enhanced phonon scattering. The host can exhibit anisotropic thermal conductivity which reduces its thermal conductivity perpendicular to the direction in which it was drawn. The nanostructure-host composite can be cut into pieces and assembled into efficient thermoelectric devices for use in cooling or electric power generation applications. Other embodiments are described and shown.