Methods of manufacturing an optical device can include, in some implementations, providing a substrate having a first polymeric layer on a surface of the substrate and a second polymeric layer on the first polymeric layer, forming first openings in the second polymeric layer to define an etch mask composed of material of the second polymeric layer, and etching to form second openings in the first polymeric layer, wherein locations of the second openings are defined by the etch mask. A material is deposited in the second openings to form meta-atoms of a first metastructure, wherein adjacent ones of the meta-atoms are separated from one another by polymeric material of the first polymeric layer. Optical devices including metastructures can be formed, where meta-atoms of the metastructure have a relatively high aspect ratio.