Unfortunately I don't know. I think it will depend on the actual tooling you
>use to create it, it may be accurate but it will also vary depending on your
>bend Allowance.
Construct it at the neutral surface. That remains a surface constant in size, bent ot unbent. Offset that surface to get the inside or outside surfaces in both the bent & unbent forms. Don't forget which is which . IF you can do it in SW ....