We have seen how organs can regulate complex material selfassembly. This section explores how to grow such multicellular tissues, notably from stem cells. Biological systems consist of numerous interacting components organized across scales, including molecules, cells, organs, and entire organisms . At the macroscopic scale, top-down approaches extract materials directly from organisms, such as tree trunks, cotton, or silkworm cocoons. At the microscopic scale, bottom-up manufacturing produces recombinant proteins (e.g. bio-based polymers ) or guides material production (e.g. concrete biohealing 217 ).