Answer:
You use me between your head and your toes the more I work the thinner I grow.
What has 4 fingers and a thumb but is not living?
I come in different colors and shapes. Some parts of me are curvy, some are straight. I look like I can belong anywhere but there is only one right place for me. What am I?
My rings are not worth much, but they do tell my age. What am I?
I sleep by day, I fly by night. I have no feathers to aid my flight. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.