13" pizza pan separator (found on ebay, the rougher the better)
9" pizza pan separator (found on ebay, the rougher the better)
variety of orange and red spray paint
hammers of varying size
a piece of concrete or rough brick/paver (from the backyard!)
heavy acrylic paint (Liquitex Heavy Body Alizarin Crimson Hue from Michaels)
Step 1: Prepare the discs.
I found that using varying metal hammers was good for getting the different dents and dings. The mallet was good for reshaping, as hammering on a raised surface tended to warp the discs. In the end I ended up with 2 slightly bowl-shaped discs with heavy markings on 1 side.
Once you've gotten it sufficiently beaten, you'll want the first layer of paint. I used varying coats of yellows and oranges on the smaller disc, and oranges, reds and browns on the larger. Its also useful to do some more banging in-between coats to give it that rough layered look. I also tried to do the shadowing (left darker than right) using some varnish to highlight the dents. I also found that wiping with a cloth after spraypainting was good for texturing.
Once you get to a happy place and no longer feel the need to beat or paint your discs, you are ready to assemble. I punched 2 holes in the big disc (making sure they'd be behind the small disc) and ran some picture frame wire through and twisted them together. Then I used an epoxy glue (cause it was laying around) and glued the small disc to the large one (and coated the hanging wire for good measure).