1) After a forged form is curved, it is still possible to widen areas starting with a heavy, wide raising hammer on the horn of an anvil. A curved stake will also work. The heavier the stake, the faster the metal will move.
2) After some width is established, go to a narrow, heavy raising hammer to widen the form further. Aim the hammer blows in the center of the plane and work your way to the edges.
3) Final planishing can be done at this point or forge on if you like.
