this is my first instructable so sry if you dont get it.
materials:
1.mp3 case(the case that you get when you buy the mp3
if you dont know what I mean see picture 2)
2.exacto knife
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)

Step 2: Holes

cut holes or drill holes where desired not to close to mp3 jack because there might not be enough room for the speaker jack to go into the mp3 jack.

Step 3: The Speaker

sorry i forgot to add the number 3 in the material list so ill show you how to make the speaker......
well all you need is an audio jack 3.5mm or 2.5mm or whatever type you have, wire 2 strands, soldering iron, solder, and a speaker.
step 1:strip the wires but not to long and solder them on to the audio jack.
step 2:then do the same thing in step1 but solder them onto the speaker.
done

Step 4: Hook It Up

turn the holder around and place the speaker on top of the holes you made in step 2 and tape it in place or hot glue it in place and tape the wires down so they don't move.
and now put your mp3 on to the holder and hook up the audio jack into the mp3 jack and turn on your mp3 and listen to your tunes and recycle or you can say reuse.