It is expected that thermal radiation from a thick polymer film could be used for narrowband thermal emission purposes. It is straightforward to experimentally show that a 3 µm thick polyimide film can absorb almost 100% of incident thermal radiation at its primary molecular absorption band. However, the emission of radiation was not efficient at the the same wavelength, primarily due to strong re-absorption. The search for wavelength-selective thermal emitters is informed largely by Kirchhoff's law, according to which thermal radiation energy output is directly proportional to absorptivity in a particular spectral range and at a given temperature. One of the most direct ways of exploiting this effect relies on selection of natural materials or synthetic composites with appropriate electronic and phononic band structures, however, the best attainable performance and the degree of control that can be exerted in this case is fundamentally limited by physical chemistry considerations. A complimentary method of tailoring absorbance and, by extension, emittance behavior relies on wavelength scale structure patterning to manipulate electromagnetic mode propagation and confinement. Examples of such structures harnessed for thermal emitters include photonic crystals, and, in particular, different types of metamaterials -artificial wavelength-scale periodic arrangements of metal structures.