Is this BMW’s future Electric Car?. Dunno, but watching the news these days it seems like pretty much everyone has an EV on the drawing board.
One of the options when making a battery box is to use a thick plastic “board” and weld it into a box (I can’t remember the material’s name). To do this you’ll need a plastic welder. I ran across some plastic welding videos recently along with a wikipedia article on it. Here’s the videos: one, two, three, and more.