Figure 7 Prototypes of topological mechanical metamaterials Panel b is adapted from REF. 45 under a Creative Commons license CC BY 3.0. Panel c is adapted with permission from REF. 48, American Physical Society. Panel d is adapted with permission from REF. 40, Macmillan Publishers Limited. Panel e is adapted with permission from REF. 51, Macmillan Publishers Limited. Panel f (left) is courtesty of H. Hostettler, ETH Zürich, Switzerland. Panel f (right) is adapted with permission from REF. 41, National Academy of Sciences. Panel g is adapted with permission from REF. 42, National Academy of Sciences. Panel h is adapted with permission from REF. 44, AAAS. Bertoldi, K. et al. (2017) Flexible mechanical metamaterials Nat. Rev. Mater. doi:10.1038/natrevmats.2017.66