Building space into solids is the focus of the 2025 Nobel Prize in Chemistry, which has been awarded to Susumu Kitagawa (Kyoto University), Richard Robson (University of Melbourne) and Omar M. Yaghi (University of California, Berkeley) “for the development of metal–organic frameworks (MOFs)”. These materials, composed of metal ions or clusters linked by organic molecules, contain permanent and tunable cavities that have transformed how chemists design in the solid state.