In my experience soft, thin sheet-like AK steel, aluminum, copper, etc., can be worked hot, cold, or both. Raising these copper petal-shapes by both stretching the centers and shrinking the edges is most easily done mechanically. For this story though, I will illustrate the hand working methods I used for years before developing my time-saving tools.

The simple ``s" shape was first worked into the blank and then, according to the layout marks, the center portion was worked into the bag with the big mallet, and planished.

The edges were then pulled down by ruffling with the hand tool...

and working the metal into itself with the trapping mallet ...

Lotus petals worked with mallet

Planishing edges

Ruffling with the hand tool

Trapping with the mallet