Fig. 5.

Construction of 3D structural color objects. (A and B) Schematic diagram and optical image of a yellow pyramid-structured structural color hydrogel. The hydrogel had an integrated structure and could be hung in the air in B. (C and D) Schematic diagram and optical image of a blue hydrogel block with a 3D triangle stacked green object inside. (E–H) Schematic diagram and optical images of the 3D integrated photonic paths in a hydrogel block. The images were taken under natural light (F), 550 nm monochromatic light (G), and 450 nm monochromatic light (H), respectively. (Scale bars: 5 mm.)