Abstract: A method for fabricating three-dimensional structures. In-flight heating, evaporation, or UV illumination modifies the properties of aerosol droplets as they are jetted onto a target surface. The UV light at least partially cures photopolymer droplets, or alternatively causes droplets of solvent-based nanoparticle dispersions to rapidly dry in flight, and the resulting increased viscosity of the aerosol droplets facilitates the formation of free standing three-dimensional structures. This 3D fabrication can be performed using a wide variety of photopolymer, nanoparticle dispersion, and composite materials. The resulting 3D shapes can be free standing, fabricated without supports, and can attain arbitrary shapes by manipulating the print nozzle relative to the target substrate. Multiple materials may be mixed and deposited to form structures with compositionally graded material profiles, for example Bragg gratings in a light pipe or optical fiber, optical interconnects, and flat lenses.