I had a cute little lunchbox that looks like a guitar amplifier, and then at Goodwill I came across some Paper Jamz speakers, and the result is obvious; I made my lunchbox play music. Then, I took some pictures of it.
The short form, which is all you're getting, is that I took the guts out of the speaker, and then cut the back out of it to use as a template. I used masking tape to attach it to the back of the lunchbox, and then sprayed it with a can of Citadel Colors white waterbase paint that I've had since approximately the dawn of man, which produced a painted template on the back of the can which flashed dry in seconds. This template was cut out of the back of the can using a utility knife and no gloves (don't try this at home, kids!) and then it was placed on the inside of the can to prevent rattling of the amplifier section.
The transducer itself was damaged in the act of removal, so now I know how to do it properly: use a razor blade scraper. But I managed to repair it with CA glue, aka "super glue", which is also what I used to attach it to the lid. Packing tape was apparently used to attach the cup to the rear of the cardboard box which served as the original sounding board, and it is what I used to attach it to the rear of the lid.
The sound is about what you'd expect, a little bit tinny. There's no volume control, so you need to use your device's volume control. There's some rattling of the lid against the body which I will solve later with some soft touch tape. But the sound quality is actually fairly good and the volume level is similar to other portable speakers, so not only is the novelty value high, I consider this to be a great success.
Transducers alone cost several dollars when you can even find them, so getting these for a dollar with an amplifier, cable, and transducer is a super deal. If you see these for a buck or two (these were liquidated from wal-mart before they hit goodwill somehow) by all means, pick them up and send me their contents :)