Mimicking the brilliant structure-based coloration of chameleons, butterflies, and opal requires creation of highly ordered layered structures at length scales a thousand times thinner than a human hair. This work leverages precise tuning of processing conditions during 3D printing and the self-assembly behavior of highly branched ‘bottle-brush’ block copolymers to create vivid photonic crystals on demand from a single ink solution. By programing printing conditions to modulate assembly kinetics, nanoscale layer formation during printing can be arrested at different stages, to achieve remarkable tuning of photonic properties. Our research supports the enormous potential of integrating directed assembly and additive manufacturing to unlock new material properties in a scalable, industrially relevant way.