Objective: To make a piping tip from a soda bottle,

Which of the following solutions is more sound in terms of naive physics reasoning?

Options:
(1). screw on the cap, cut a star shape into the cap with an X-acto knife, and then slice off the top of the bottle 1" from the end with the knife..
(2). screw on the cap, cut a star shape into the cap with a serrated knife, and then slice off the top of the bottle 1" from the end with the knife..
(1).