All you need is a pair of old sweatpants (or at least the leg), a sewing machine, and some creativity!
Step 1: Preparation
Cut off a leg from your sweatpants and get your mp3 player-you'll need it to help you measure how big the 'sock' should be
Step 2: Making the Pencil Marks
Turn the leg inside out, and slide your mp3 player into the bottom of the leg, where the elastic is. Make sure it is on the far left or right of the leg to minimize sewing. Next, take a pencil and mark the edges of the player.
Step 3: Sewing
Using your sewing machine (or you could do it by hand if you want, but i wouldn't recommend it) sew along your pencil lines, making sure to include the elastic part.
Step 4: Cutting
When you are done sewing, take some scissors and cut around the stitch, but leave a little bit of fabric so the stitch doesn't unravel.
Step 5: Be Creative!
Finally, turn your sock inside out so that you are looking at the right side again, and add whatever flare you want! I put a red button on mine :) THE END