Non-Technical Summary: Self-assembly refers to the spontaneous emergence of well-defined structures from an initial disordered state. Common examples include the formation of soap films, the folding of proteins and nucleic acids, as well as the formation of crystals. Self-assembly is a powerful bottom-up approach to materials synthesis. While capable of generating intricate structures, equilibrium self-assembly suffers from limitations. It requires microscopic constituents that exhibit riotous dynamics driven by thermal noise. To overcome these limitations, this project will develop a paradigm of active assembly for generating materials from building blocks that exhibit no thermal motion. Non-thermal Velcro-like bundles of filaments are placed in an active fluid. Spontaneous flows generated by active fluid endow passive bundles with enhanced dynamics. These bundles move chaotically, stick to each other, generating permanent connections, and assembling three-dimensional elastic networks, whose structure and mechanical properties cannot be realized with conventional self-assembly methods. The proposed research provides a powerful platform for generating new materials with unique properties. From a societal perspective, the proposed project will provide rigorous interdisciplinary training to graduate students. The project will also provide invaluable research opportunities and extensive mentoring to undergraduate students from UCSB and throughout the California State educatio