Fig. 5. Demonstration of the ability for a 4D-printed structure to be reprogrammed from its permanent shape into many different configurations that are structurally stiff at room temperature and then to be returned to its permanent shape upon heating.

(A) The deployed permanent configuration of a compact lattice after heating, which is same with the activated structure in Fig. 4A. This shape is also the recovered shape after reprogramming and heating. (B) The reprogrammed saddle-cylinder shape. (C) The reprogrammed compressed-twisted compact shape. (D) The reprogrammed semisphere/dome shape. (E) The reprogrammed in-plane fan shape.