Polyurethane in thin sheets is not particularly stiff, nor particularly light relative to its stiffness. It won't stay in a cone shape unless it's sealed and inflated.
Rolled cones are relatively easy to do in aluminum, and in the very thin steel used in 'tin' cans.
How do you plan to close the seam, and attach the cone at the ends to, whatever?
Thanks for the post. The rocket is propelled by water with 50 to 60 psi air in a one liter soda bottle. So the pay load has to be really light. Expectation is to keep the rocket in air for about 10 seconds since it needs to carry a egg.
What exactly do you mean by "payload?" Or are you simply talking about a nose cone? If the latter, they're readily available in most decent hobby stores.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
You are right. I am looking for nose cone with light weight. Height roughly 4 ft or 3 ft to give a try. May I know any website or store where I can buy. Thanks for sharing.