ChromaFlow is a handheld digital cosmetic manufacturing system that measures each user’s lip bio-optical profile, predicts the final on-lip result, and manufactures a personalized lip formulation on demand. Multimodal optical sensing captures color and surface characteristics that cause the same cosmetic to appear differently across users. A physics-informed AI converts these measurements into a Digital Lip Twin, predicts how a formulation will appear on the user’s lips, and performs inverse formulation to calculate the base-and-pigment ratios required for the selected target color and finish. The device then translates this digital recipe into a physical cosmetic through nanoliter-scale piezo metering and precision microfluidic mixing, delivering the finished formulation through an integrated applicator. By connecting measurement, prediction, formulation, manufacturing, and application in one workflow, ChromaFlow moves personalized beauty beyond recommending existing shades or dispensing predefined recipes to real-time, user-specific cosmetic manufacturing.