 This paper proposes a novel method for controlling the physical and chemical properties of hydrogel-based organ-like cultures over time. The authors demonstrate how this technique can be used to direct the growth of neural axons, control cell migration in developing cancer organoids, and promote cell polarity in liver organoids. Additionally, they show how the hydrogel composition and shape can be used to control the morphology of lung tip bifurcations. This article was offered by Anna Urtuolo, Giovanni Giuseppe Giob, Isiao Dong, and others.