When my oldest girls were about 5 and 6 years old, they liked to make little books. They would get several pieces of paper (it didn't matter to them what kind), fold it over, staple the 'spine' edge and make a 'book'.
They collaborated on one book, “The Spider and the Sun”, that I considered thoughtfully written and cleverly illustrated. I tucked it away with some other schoolwork from that year. I saw it occasionally and was still struck with the creativity of the book, especially for the age of the girls at the time.
Over the years, I learned to 'publish' my children's books into a softcover book using a photo book publisher. When my oldest daughter got married recently, I thought it would be a fun gift to turn her book into a 'real' book using my photo book method.