While I was tidying a little up I found out some strange stuff; then I decided to give another chance and use to a little piece that remind me of a casette :)
Step 1: Speakers and Welding
I bought a good size speaker to fit in the holes. After that, I welded them to a cable and a minijack.
Step 2: Make Holes
I needed to make a groove on the "box" that contained the speaker, so I used a Dremel to get it sorted out and make a little hole for the cable in it.
Step 3: Glue All
Now, with contact glue, I glued the cables through the holes I made with the dremmel. With a glue gun I attached the cables to the back.
Step 4: Results!
Here you can see the results! :)