Inspire to Make recently released this video on how to make a pair of unique headphones with two .40 S&W casings, some spare headphones, an assortment of tools, and a little bit of creativity. No verbal instructions is given, but the video is easy enough to understand. Finding earbuds to fit the brass might be the hard part.
Does this pique your interest? Or would you rather save all your brass for reloading instead?