Fig. 3: Structural color regulation.

a Scheme of structural color observation of Lego brick structure from the different viewing angles (α) under diffusive lighting condition. b–f Optical images of the Lego brick structure with viewing angles (α) from 0° (b) to 15° (c), 25° (d), 35° (e), and 40° (f) under diffusive lighting condition. The Lego brick structure is printed with PS particle diameter of 230 nm. g Optical image of the customized bracelet structure composed of 3D printed bear structures of different structural colors and black plastic beads. The bears from the left to right are printed with PS particle diameters of 265 nm, 214 nm, 245 nm, 192 nm, 230 nm, 214 nm, and 265 nm, respectively. The inset of the solid white box on the upper right is the 3D bear model. h Optical image of a hand model wearing the customized ring structure, which is fabricated by connecting the 3D printed bear structure with golden plastic beads. The insets of the white dotted box in the middle and the solid white box on the upper right are the optical images of the magnified ring structure and the 3D bear model, respectively. i Optical image of a Barbie doll wearing the customized earring and necklace structures. The necklace structure is a designed cylinder grid structure printed from 214 nm PS latex particle with decorative chain (metal rings) passing through, and the earring structure is the Lego Brick structure printed from 214 nm PS latex particle with its top ring connected with an ear stud (metal). j Reflectance spectra of the 3D structures printed from PS latex particles with different diameters. k Composite optical images of the 3D structures printed with varying PS latex particle diameters and printing speeds. Scale bar: 1 mm. l Phase diagram of the characteristic peak wavelength versus PS latex particle diameters and printing speeds.