I have gotten over ten requests to post stuff on how I made this and what it looks like. Here is a pic:
Note that this version only has three rings in the bottom, the version I use has five.
To start, I aneal the bottom by heating it pretty hot. Use caution here, too hot will melt the aluminum. I use a small bead of olive oil in the center to tell me. When it starts to turn brown, then it is hot enough.
I use a slotted form shaded to match the radius of the pot. It extends to the center most ring, about an inch in diameter. It is roughly 2" wide and is hard, "rock" maple. I use a small ball/peen hammer for the top. I tap the metal gently into the dimples all around. Shift, tap, shift tap, and so on. I then use a smaller piece of rounded wood to smooth out the dimples left from tapping. I have an old push round rod that works well as the final finishing tool. Then I scrub the whole thing with steel wool.
This is an extraordinarily simple process. The tapping and burnishing will "work harden" the metal, again.