So start simple. Experiment first with a folder that contains a case study and drop in whatever PDF and images relate to that case study. Then consider your "case study" type what data needs to go onto it, and who and when does that data get added.
You can then consider improving the linking between the "case study" and the "supporting documents." At some point you will probably want a "supporting document" aspect.
You may also want to have workflow around the case studies, since there is probably some control for case studies.