Yes, it was mild steel stock that I used to make the dish. I am not sure of the gauge, but am guessing around 14-16. It was not very thin and not very thick. Just a small sheet of something I had laying around.
A ball peen hammer and a raising hammer were used to dish it in the swage block.
Dished the small section of mild steel sheet in the swage block, cut it out with some shears after dishing, ground the edges flat on my belt sander, hand sanded it bright inside and out, applied heat with a propane torch to generate tempering colors of my choosing, covered in beeswax coating. Done.
To all the beginners out there - The use of tempering colors is a great way to "color" your steel project. You can get colors in this palette: http://commons.wikimedia.org/wiki/File: ... _steel.jpg
From what blacksmiths call "straw" colored to bronze to purple to varying shades of blue. All of these colors correspond to the surface temperature of the steel being tempered.
As you can tell from the photo, I stopped heating when the steel turned a deep copper/bronze color. What you are chemically doing is creating various types (and colors) of iron oxides (e.g. rust) on the surface of the clean steel by the application of heat. This color will scratch off, it is only on the surface. By itself, the color is about as durable as an inexpensive paint, maybe a bit more. However, it is attractive and the cost is right! Your finished surface must be protected with your favorite coating or the steel will simply continue the rusting process over time. A clear acrylic paint or clear polyurethane would have protected it much better than beeswax, but I wanted to keep it traditional.
The dish in the photo is kept inside, near a sink in the kitchen and is about five years old, so it isn't rusting. It is also just a display piece and isn't used for anything that might abrade the colors off or scratch through the beeswax protective coating.