The Bottle is the object the whole loop was designed around. Its shell is spun from recovered aluminium, smelted with hydropower, and finished without paint so it can be melted down cleanly at the end of its life.

Every part is replaceable. Caps, seals and the carry loop unscrew in seconds, and spares ship free for ten years. When it is finally done, a prepaid label brings it home and it becomes the next one.