More recent advances have enabled systematic control of the assembled structures of extended gel networks of plasmonic nanoparticles. For single-and multicomponent nanoparticle gels a key to connecting experiments with simulation has been the ability to achieve reversible and reproducible assembly, aided by the introduction of bifunctional linking moities that leverage dynamic covalent chemistries. Analogously, quantitative understanding of the optical properties of compositionally mixed nanoparticle metasurfaces has been facilitated by experimental methods for achieving controlled assembly at liquid-air interfaces. Integrated experimental and simulation studies have also benefitted from methods for synthesizing highly uniform doped metal oxide nanocrystals with plasmonic resonances that can be chemically tuned across the near-and mid-infrared, approximately independent of nanocrystal size, by controlling the concentration of dopants introduced during solution phase synthesis. Spherical, tin-doped indium oxide (ITO) nanocrystals capped with organic ligands are primarily featured in the experimental examples highlighted here.