It's a simple support I've designed to hang the structures to the wall.
It works using a simple wall pin like this (https://res.cloudinary.com/clippings/image/upload/t_big/f_auto/v1542202926/products/pin-wall-hanger-set-of-6-zieta-clippings-11115411.jpg).
Simple glue the support to the tree 2d art, I've used three supports for each part of the art (but I've also doubled the size of the wall art), it's up to you where to glue them, just put them in parts where they will be less visible from the other side.
Hope you enjoy!