I m using maps illustrated from coutries to organise different mind palaces, in the moment I m using my coutries, Portugal.
Example: coimbra- books- monuments or other spaces like coffes, etc for loci the book I want to keep stored.
Have you tested this? I advise you to try. But such an approach is unlikely to be effective. The fact is that our brain does not perceive a 2D image as something that needs to be remembered. The hippocampus is designed for orientation on the ground and stores in our memory only those objects that have clear coordinates in space-time. It is better to simply be transported to other countries using satellites and cameras. Rooms from movies and videos are also suitable. It is very good if you sketched a similar map for the area that you have chosen as the palace of memory, in general, drawing is a very useful hobby for the mnemonist.Just remember Mikhail Kuni. But to use cards as palaces of memory is an unpromising idea.