Hi Aurea. We did something very similar for our sons. We called it their "Books of Joy". They were meant to be tangible reminders of the things that bring them happiness, that they could look through in times of distress to remind them that there are good things in their lives. I helped them to alter board books with gesso and acrylics to make them, and then they collaged and drew a different theme for each page.
The cute and funny thing was that they didn't put in any people, more like dogs, crocodiles, Bionicles etc. I asked my son why and he said that if he was upset, and saw a picture of the person who had made him upset it wouldn't bring him joy. Made sense to me.