From Sock to Glasses' Case

I'm going to England in two weeks, and need to pack light. My sunglasses are the kind that fit over my regular glasses, and the case that came with them is ridiculously bulky. I've been wondering about something to protect them from scratching that won't add bulk or weight. Quilted case? No -- still too bulky. Then I remembered my Miss Matched Socks -- the kind where you get three in a pair and each one is different. I have some that are black with big polka dots, wide black and white stripes, and narrow ones. Here are the narrow ones with the glasses:

Do they fit? Yup.
How long does the case need to be?
Serge or cut and sew:
Yaayy! Very thin and lightweight. And kind of cute.