So pretty... Dunno if I'd use the rainbow idea. It would be pretty with blues and purples instead.
$US5.50 Spanish Mandala is made in Overlay Crochet technique. This easy to follow pattern (18 pages) is written for one size. It contains step by step full written instructions in English using standard crochet abbreviations and US terms (stitch guide is given in the pattern). It also contains lots of pictures explaining all the tricky and difficult places.
Yin Yang dish pattern, by goolgool on Ravelry. 2 sizes available - 6" dish, 4" dish. crochet home decor, trinket plate, rings plate, ring bearer box, alternative wedding.
Spanish Mandala design was inspired by ceramic handmade plates from Spain. this mandala is made in overlay crochet technique, with lots of front post stitches. The crocheted fabric is quite thick, and it is ideal for making a round pillow. Check details on http://www.lillabjorncrochet.com/2016/05/spanish-mandala-create-your-own-sun.html