I have seen the instructables on making a single speaker, but I'm showing you how I made a stereo version. This is my first instructable, so constructive and positive feedback is welcomed.

Items Needed:

1 pair of wire cutters
1 pair of scissors
1 razor blade
1 nail
1 hammer
1 roll of electrical tape
1 heat source
1 gameboy advance case
1 long strand of speaker wire*
2 speakers
4 squares of foam

*The speaker wire I used was found at a random parts shop. I'm not sure what it's called, but it looks like the cord part of earbud-type headphones, but double the wire, all converging into one connection piece that plugs into the headphone jack.

Step 1: Create the Wire Holes

Hammer two holes in the back of the gameboy case and string the wire through. If the hole is too small, stick the nail halfway through and rotate the hole bigger. The case is aluminum, and is reletively easy to hammer through.

Step 2: Create Speaker Holes

Now that you have the wires in the back, you have to make holes in the plastic lid of the case so you can hear the music better. At first, I tried heating the nail with a lighter, but it worked less effectively as I first thought, so instead I used a 45watt soldering iron. Use what you feel comfortable with.

If you do use a soldering iron like I did, wait for it to heat up, then poke through firm at first, then when the plastic starts to melt, loosen the pressure on the plastic, and it'll poke through slowly. Run the tip through the hole a few times to make sure it stays open enough. Dont't fully remove the tip until the hole is to your liking. Repeat as many times as deemed fit to allow a good sound. I made 10 holes.

After the plastic cools, you're left with an ugly looking puckered effect from the heat. Use a razorblade to cut the extra plastic around the holes inside and out of the case until you have holes and not burnt plastic around the holes.

Step 3: Create Speaker Holders

Take the foam squares and fit them inside the case, cutting if needed, to fit the case, allowing room for the lid to close and clasp shut, as well as a small spot for wire relief later on.

Cut two holes, not divits, to allow room for the back part of the speakers to sit, making sure they are spaced to allow the lid to close, and the speakers don't touch. The speakers themselves are about the same diamiter around as a soda can.

Once you have two holes, pull the wires on the speakers through the holes, folding them back a bit, and push the speakers in enough to sit. Repeat with the second speaker.

Step 4: Connect the Wires

It's self explanitory. Connect the red to red and black to black for both speakers. Wrap small pieces of electrical tape around all exposed wire and curl into the case.

*It's come to my attention that there may be some confusion as to the type of wire needed. Some have asked for elaboration into the connection of the wires. The wire I used was not the same as the .99cent earbud headphones or wire with red/green/gold inside. It was a wire that had two red/black wires that had the usual headphone jack. I'm not quite sure what this type of wire is called, so anyone who knows, please tell me so I can post it.

Step 5: Finish Up

With the wires connected, the speakers inside the foam, and the foam inside the case, close the lid of the case and plug into whatever will accept the standard headphone. Since the housing is a Gameboy Advance case, most likely found at your local video game store, you can attach a strap to it and carry it around. It's a bit louder than the single speaker systems I've seen, and it's stereo.

Enjoy.