help on plastic part for rocket

hey all
starting to build my jet pack from scratch now ,so am looking for a bit of help on the rocket at the top of it.as i live in the UK i am looking to buy something from a diy shop or similar that will be roughly the same shape as the rocket.i will be making the rotj version with the badly damaged back face(by han with the axe) so looking to get a move on with this as i feel its gonna take me a while. i will post pics as i progress.any help on this would be great.
cheers
paul

I foudnt that automatic transmission fluid funnels are close to the shape of the bottom of the rocket.