The pyrenoid is a chloroplastic microcompartment in which most algae and some land plants condense Rubisco as part of a CO2-concentrating mechanism that improves the efficiency of CO2 assimilation. Approximately one-third of global CO2 assimilation is performed by the pyrenoid, and engineering a pyrenoid-based CO2-concentrating mechanism (pCCM) into C3 crop plants is considered a promising strategy to enhance yield capacities and resilience to the changing climate. Although our understanding of pCCMs is largely based on research in the model alga Chlamydomonas, recent work in other species is helping to build a broader appreciation of the variety of mechanisms that regulate Rubisco phase separation, and pyrenoid architecture and functionality. From an engineering perspective, these advances offer an exciting range of new components to explore. I will discuss our recent efforts to reconstitute key pyrenoid architectural features in planta, and how advances in other pyrenoid-containing species are helping to accelerate progress towards achieving a functional pCCM in a C3 plant.