Using FFF, we fabricated the expanded structure (a0=17.8 mm, 7.35 mm height, Figure overlay) from polylactic acid (PLA) on an aluminum substrate. FFF provides a rapid, automated and highly reproducible means of fabricating complex geometries from thermoplastic polymeric materials, allowing straightforward introduction of arbitrary defects into the structure. FFF also provides a tradeoff between print time and part density (which affects refractive index) by tuning the infill percentage. For PLA (bulk n=1.64), maintaining a refractive index above 1.55 for reasonable print times was a key technical challenge in this work. We have selected slicing parameters (Table ) which result in print times of ~30 largely unsupervised hours while achieving a refractive index of ~1.61, as determined from comparison to the simulated transmission spectrum. Specialty filaments with high refractive index could be used to produce structures with lower infill percentage and thus lower density, further reducing print times and providing a flexible means for introducing refractive index gradients as a degree of freedom in device design.