So, in this video I cut to the chase and show you how I built a DIY waterproof Bluetooth speaker “boom box” in a Harbor Freight Apache 2800 case using a single 6x9 speaker. I went with the Polk 6x9 (you can swap in other 6x9 marine options), a KBT 4Ah lithium battery, and the 1001u Bluetooth amp running 24V. The whole point is to get something rugged and outdoor-ready—basically Turtlebox-inspired—but built your way, with parts you can actually source and replace. I walk through the layout, cutting the case, mounting the speaker with a 3D-printed spacer (optional, but it centers perfectly), and sealing everything with silicone so it stays waterproof. I also add a latching power switch and a waterproof DC charge port so I don’t have to open the case every time I want to charge it. Wiring is straightforward (very similar to 12V wiring), and I use WAGO lever connectors to keep it quick and clean. My takeaway: for around $160 give or take, this thing is loud and clear—at half volume I could still hear it clearly from about 100 feet away. It’s more portable (and cheaper) than the big party box style speakers, and you can customize everything: speakers, case size, even pairing multiple amps for more speakers.