Book du jour

The "maps folded into a book" (see them here) intrigued me and I tried to reconstruct them from memory. Failed utterly! At the top of the photo is this morning's attempt, looking rather like a model for a new shape of pasta -

Back to the photos, then, and some drawing. Result: understanding, and success!

A double-map-fold from a scrap of tracing paper (during which I learned which folds should not appear) -
yet they add a linear element to the transparency effect ... perhaps inessential folds as marks could be a way to develop these books -
A simple cover -