Making A5 notebook leather cover. Leather craft

I made this cover to order as a gift to the artist. In fact, it was originally intended for a sketchbook, but it will also work for notebooks of the same format. The cover is designed for a notebook up to 20mm thick. At the request of the customer, on the one hand, I made a pocket for a plastic card 55 * 85mm, and on the other hand, a ruler holder. The peculiarity of this cover is a compact solution for fixing the handle, which is a lock.