Figure 4 4D printing schemes and time-evolving structure geometries Panel a is adapted with permission from REF. 153, Macmillan Publishers Limited, and REF. 156, AIP Publishing. Panel b (top) is adapted with permission from REF. 153, Macmillan Publishers Limited. Panel b (bottom) is adapted with permission from REF. 158, Macmillan Publishers Limited. Zhang, Y. et al. (2017) Printing, folding and assembly methods for forming 3D mesostructures in advanced materials Nat. Rev. Mater. doi:10.1038/natrevmats.2017.19