In case you have an old ammo box lying around, you might want to turn it into a speaker.
This was apparently a project that is was intended to be a conversion of a .50 caliber ammo box into a functioning speaker for an MP3 Player, notebook, or portable device for about $50.
I have no idea if the builder of this particular DIY project succeeded in his or her goal. It looks pretty minimalist, and I wish I knew how much volume it can produce.
Perhaps if I have an ammo box at home that I can use.