From Coils to Cages Self-assembly strategies that mimic protein assembly, such as the formation of viral coats, often begin with simpler peptide assemblies. Fletcher et al. (p. 595 , published online 11 April; see the Perspective by Ardejani and Orner ) designed two coiled-coil peptide motifs, a heterodimer, and a homotrimer. Both peptides contained cysteine residues and could link through disulfide bonds, so that the trimer could form the vertices of a hexagonal network and the dimer its edges. However, these components are flexible and, rather than form extended sheets, they closed to form particles ∼100 nanometers in diameter.