Sometimes I enjoy colouring mandalas and patterns by drawing or doodling inside the spaces, rather than filling them all with colour in the usual way. In this page from my Easy Mandalas Colouring Book, I drew in a simple stripe pattern with fine liner pens, and added some shading with pencil.
Easy Mandalas was my first mandala colouring book, and it has fifty designs that are simple to colour – you can see them all here. It is for sale in paperback on Amazon.