In this tutorial, we learn how to build a subwoofer for a Mini Cooper. Start off by cutting the wood so it's to the exact sizes that you need. Next, attach the walls of the subwoofer together with a screwdriver and screws. After this, apply wood glue to the inside of the wood to make sure it's stuck together. Next, make a circular piece of wood for the speaker, then cut a hole in the back of the box. Insert your speaker to the subwoofer and string the wires through the back. When you are finished, place this in your car and enjoy your music!