The next frontier for protein design is an automated strategy for designing huge functional repertoires. We are developing methods for design and synthesis of millions of substantially different variants followed by high-throughput screening to characterise the designs, and ML to deepen our understanding of protein design principles. We are applying this strategy to the design of new hydrolytic enzymes, single-domain camelid antibodies, fluorescent proteins, and therapeutic antibodies. These methods will enable rapid and effective discovery and optimisation of biomolecular activities in protein engineering, synthetic biology, and biotherapeutic design.