Figure 4.

Illustrations of 2D and 3D structures produced by the composable-gradient DLP printing technique. (a) The continual gradient of colors in the slices of a hydrogel pie printed by mixing merely three colored PEGDA inks. The inks in the Eppendorf tubes represent the colors collected after mixing before printing. (b) The 2D structures including a circle with 4 color gradients, a heptagon with 7 color gradients, and a vascular network with 4 color gradients, generated by mixing two differently colored PEGDA inks at different ratios followed by printing. The corresponding designed patterns are shown at the left, while the actual printed results are presented at the right. (c) The 3D constructs generated using PEGDA inks showing shapes of a cube, a pyramid, and a twisting hollow vase, featuring color gradients in the vertical direction. (d) The 2D maple leaf with horizontal gradients and the 3D maple leaf with vertical gradients printed with the same composable gradient colors mixed from green to red in real time during the printing sessions. (e) The Rubik’s cubes consisted of 2-by-2-by-2, 3-by-3-by-3, and 6-by-6-by-6 units presenting color gradients from discrete to continual.