Nelson developed a theory to describe elastic shells that are so thin that thermal fluctuations are important; this modifies the usual thin-shell theory. The results are in accord with the measurements of Weitz who creates very thin elastic shells using capillary microfluidics to fabricate a bilayer structure formed from diblock copolymers. These structures are used to encapsulate delicate peptides and ensure their efficacy for skin care when used in cosmetics. A start-up company based on Harvard-MRSEC-supported research has commercialized these structures.