Hi Sharif, or probably a good way to proceed would be a kind of combination approach.

That would be to have a big outer surface to start with but then build some sweeps that follow along it and intersect those sweeps with the surface to get the curves to trim the surface with.

That way sweeps can be used to help make the general outline, but you'll have a fully flush surface because instead of trying to make sweeps align with each other you'll have one big larger surface that starts out all continuous before it is cut up.

- Michael