CAR roofs, how to make them

[torikoos]

Hi everyone. Does anyone have good ideas / techniques/ references etc or know how to make (passenger) car roofs? I am not too bothered about the more classic shape found on pullmann etc, but particularly the rounded corners on Budd stainless cars , Budd RDC's etc . I am okay in building bulkheads / car sides etc, but getting a roof straight and with 4 matching symmetrical corners is a bit of a 'challenge' at the moment.

Any tips/tricks/references welcome.

Koos