This video shows fragments from a process of about two hours.
Here I am raising 0.8mm rectangular copper sheet, doming it from the center in a soft slope towards all edges which lay flat on the table.
Due to the hardening of the copper as it is worked, I annealed (and pickled, which is not shown) the metal several times to re-cristallise the molecules.
The sheet is worked over a flat anvil with a boxwood hammer and a steel hammer, the latter has a “drop of wax” polished head that transfers this sheen onto the copper. I also used a steel burnisher for laying the edges flat.
The raising hammering motion follows a nearly-spiral pattern, from the center to the edges, and the hammering stops at two or three millimeters from the edge. This process is repeated, and little adjustments made, several times, until the desired shape is achieved and the plate doesn’t wobble when spun, which shows if the curves are balanced.
The final polish is achieved with a glass fiber brush and powdered pumice stone. After a final cleaning of grease, dirt and any oxide that may be left, the plate will be ready for enamelling.