Portable car stereo
While waiting at a red light, I noticed that inside of a FedEx truck, the driver had his own portable car stereo in the cab with him. It consisted of a wood box with three 3.5" Dia speakers on the side with the stereo (what looked like an older model) sticking out of the top of the box, vertically. I'm guessing he had it wired for a cigarette lighter adapter to power the unit and the box was held in place in the cab by bungee cords.
It looked like a great way to recycle old car electronics, wished I'd thought of it when I had to drive cross-country in a Uhaul with only an am/fm radio.