Here are some pic's.

I have been thinking of using a rectangular bottom die (male) with 3 to 4' radius l to r and a longitudial radius equal to the exterior flared radius.

The top die would be female and perpendicular to the bottom die. It would be 3 to 4' radius l to r with a longitudial radius equal to the bottom die.

I would appreciate and thought, comments, etc.

Thanks,
Herman