A group of researchers have successfully soaked proteins into large protein crystals, marking a hitherto never reported achievement. The X-ray diffraction data, which were collected on MAX IV’s BioMAX beamline, indicate that the guest proteins could follow at least some of the hosts’ structures signifying a so far unparalleled step towards using crystallographic methods to solve guest protein structures. Such insights could pave the way for major advances in biotechnology, material science, and structural studies.