Ensuring the continued availability of materials for manufactured products requires comprehensive systems to recapture resources from end-of-life and wastewater products. To design such systems, it is critical to account for the complexities of extracting desired materials from multicomponent products and waste streams. Toward that end, we have constructed dynamic simulation–optimization models that accurately describe the recovery of materials and energy from products, residues, and wastewater sludges. These models incorporate fundamental principles such as the second law of thermodynamics, as well as detailed, empirically based descriptions of the mechanical separation of materials at the particulate level. They also account for the evolution of the recycling system over time. Including these real-world details and constraints enables realistic comparisons of recycling rates for different products and technological options and accurate assessments of options for improvement. We have applied this methodology to the recycling of complex, multimaterial products, specifically cars and electronic wastes, as well as wastewater and surface-water systems. This analysis clarifies how product design, recycling technology, and process metallurgy affect recycling rates and water quality. By linking these principles to technology-based design-for-recycling systems, we aim to provide a rigorous basis to reveal the opportunities and limits of recycling to ensure the supply of critical elements. These tools will also provide information to help policymakers reach appropriate decisions on how to design and run these systems and allow the general public to make informed choices when selecting products and services.