I warn you the sound isn't great but it's pretty good for an altoids tin. Besides, if it's quiet in your room it's good enough.
*Regular size altoids tin(1.76 oz)
*Headphones you won't want back(cheap ones)
*felt(for the inside of the tin)
*Scissors or other cutting tool(optional, but recommended)
*Foam adhesive(better and neater than tape)
Step 1: Headphone surgery
I finished this before the instructable, so I am showing you the finished version. You can get the idea either way. Hope it's not confusing. This is my first instructable so comment.
Step 2: Prepare the tin
You can see I lined the top and the bottom with the felt(inside the tin)
Then cut an opening in the tin on the side so when you close the tin the cord can come out.