Step 7: Finish Cutting the Bottle Into Rings...
Continue cutting until you have reached the last section of
the bottle which can be cut evenly, typically before the neck,
until the bottle is completely cut into rings.
Keep in mind, you don't have to work with the tiny section at
the top of the bottle. It is not wasteful to use another bottle as long
as you return the scraps to the nearest recycling center.