Old leather suitcases or briefcases from decades ago are commonly found in varying states at garage sales, thrift shops, and vintage stores across the nation, popular DIY fodder for an array of upcycle projects like this and this. But here's a conversion project which tunes into a different side of the DIY spectrum...
Salvaging spare parts from one of those all-in-one home theater DVD and surround sound speaker systems, rebozoed integrated a popular and cheap $21 audio amp (visible above with the glowing dial on the right side of the case), power inlet for charging, a headphone jack, a 12 volt battery, and even a power/charge indicator. All together with speakers installed across the suitcase front, the former luggage is now an affordable version of similarly sold suitcase audio speaker models for at a fraction of the cost.
More photos and additional details available here at rebozoed's Imgur project page.