The notepads measure about 6 by 10 cm (2.4 by 3.9 inch) and are made with paint color strips from the DIY store. In fact this is all you need.
It's one out of many ideas in the book Het grote zelfmaakboek voor meisjes (literally The big DIY book for girls) by Kristel van Genugten.
It's a great book. It's very contemporary, it's clear in its descriptions and it is packed with a wonderful variety of ideas. From plaster casting to cutting stamps, from knitting to sewing and from printing to recycling. It's excellent for girls, boys, adults ... everyone.