Tapestry crochet bags

I am making an afghan using tapestry crochet, where there are different sections of different colors that I am working on at the same time. Trying to figure out how to keep the other yarn out of my way, I finally came up with the idea of cutting off the toe section of a sock, putting the yarn ball in it, and safety pinning it to the back of my work. Everything else I tried just got tangled up. Hopefully this will work better. (Edit) Wow! It's working great! I just pull what yarn I need out of the little pouch as I am crocheting. I can now handle this piece the way I would handle any large piece of work on my lap!