Figure (IMAGE) Singapore University of Technology and Design Caption Heat-shrinking induced colors of 3D printed woodpile photonic crystals. (a) Schematic of the fabrication process. Left: woodpile photonic crystal written in commercial IP-Dip resist by two-photon polymerization at dimensions well above the resolution limit of the printer to prevent structures from collapsing. Right: after heat treatment, the dimensions of the photonic crystal are reduced below the resolution limit of the printer, and colors are generated. The colors change with different degrees of shrinkage. (b) Composite optical micrographs of heat-treated woodpile photonic crystals with varying structural dimensions as viewed from the side. Micrographs of the 3D-printed model of the Eiffel Tower in structural blue (c) and structural red (d). (e) Oblique view of an Eiffel Tower printed with intentional gradient of colors. (f) Further down-scaled multi-color 3D print of the Eiffel Tower. Credit SUTD Usage Restrictions Image should be credited and used with appropriate caption License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.