1. Find an old speaker from the front of an old computer, Or just use any speaker that will fit nicely.
2. Desolder the red and black wires from it.
3. Solder the headphones wire to the speaker. Both colored wires go to the + side and both copper wires go to the - side.
4. Put the bottom foam in the tin and seat the speaker in it.
5. Pull the extra wire out through the hole so the knot is against it.