There is an urgency in the Western world to find means of slowing down and becoming calmer and more peaceful.
One of the commercial successes (apart from the myriad books on mindfulness) is the new rage for colouring books for adults.
Of course you will not find fairies or clowns or animals in these colouring books. The purpose of the books is not to practice holding a crayon or staying within the lines. The purpose of the books is to help adults relax by focusing on repeating patterns and on no particular topic.
Quite often mandalas are used in these adult colouring book. Mandalas are complicated repetitive patterns that originated in Eastern philosophy as an attempt to make a symbolic representation of the Universe more tangible.