Nature has produced a variety of proteinaceous materials, each with a set of mechanical properties tuned by evolution to adapt to particular environments. While these advantageous properties have also made many of these materials well-suited to various human needs, few protein materials can be harvested from their natural hosts at scale. To meet the demand for these materials using scalable biomanufacturing processes, our lab has developed tools and a biopolymerization platform for the microbial synthesis and processing of nature-derived, high-molecular-weight protein polymers. In this chapter, we describe the application of this platform for polymerizing a segment of the muscle protein titin and processing the resulting polymer into high-performance, muscle-mimetic fibers with a unique combination of desirable mechanical properties.