I was recycling crap around my parents house when I found the speakers. One was a car speaker and the other two were low frequency home theater surround speakers (eventually wired in paraallel).
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The speakers got wired into a cheap, two-channel amp from amazon and were secured into the suitcase with gorilla glue or mounting hardware.
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The speaker boxes were stuffed with polyfill from an old pillow and caulk was used to seal the edges.
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I recommend you guys do this because you can make a badass speaker for your phone or other device. You can add bluetooth with a simple mod, and most of the parts for this can be made from recycled things found around the house, and you can paint it however you like!