A binding designed by Carmencho Arregui, which belongs to the family of Crossed Structure Bindings.

The Expander has the essential characteristic of being able to accommodate over time more and more sections, as they can be added one by one by changing the size of the spine; because they're sewn independently from each other, sections can also be moved by changing the initial order, and playing with different colors of threads to identify the different contents.

We'll make this binding with a leather cover, flexible and durable, and we'll learn to measure it and cut it; the sections will be prepared with a variety of papers, rough and smooth for watercolor, drawing paper, writing paper...