This is for lots of types of yarn and any corresponding hook size (although I’d recommend going one lower than what’s normally suggested for the yarn weight.)

A brilliant way to use up scraps.

What you need to make a c2c bag (or indeed, a granny hotchpotch bag) is covered within the blog post linked here but there isn’t a specific written pattern. If you’re at ease with basic crochet skills, I’ve written all the notes and linked to all the things you need to make a fabulously colourful corner to corner bag.