A printing system may be provided. The printing system may include an agent distributor to selectively deliver at least one printing agent onto a substrate on a first type of supply module and a layer of build material on a second type of supply module. The printing system may include a controller to control the agent distributor to selectively deliver the at least one printing agent in patterns derived from data representing a slice of a three-dimensional object to be generated and representing an image to be generated on the substrate.