this is my first instructable so sry if you dont get it.
1.mp3 case(the case that you get when you buy the mp3
if you dont know what I mean see picture 2)
3.speaker already made with audio jack see step
thats all you need.
Step 1: cut out the hole
take out the thing that holds your mp3 and cut out a hole where the headphone jack output is.(picture 2)