The natural shape of the limb predetermined the form of the shelf. Errazuriz adapted it to his needs by twisting it and sanding the rough edges. He also applied lacquer over the branch, giving it smooth and shiny black finish. Glass platforms were added, too.
The shelf was named “Bilbao” after the street where it was found. It’s not the first time Errazuriz has used branches in his artwork. You can check out more of his nature-inspired works on his website. Also, for more creative bookshelves, have a look at this post.