I found a runover (and rusty) can of German Radeberger Pilsner beer and cleaned it up a bit then gave it the hammer treatment for an improved flat look before painting. You can see a larger view with back here.
This painting was done on a small can of coffee drink. The can seemed to be made out of something other than aluminum - real tough to flattened down.
On this cat painting I added some whiskers by cutting out some heavy-duty nylon wire I use for hanging my paintngs and then gluing them in place. Look closely around the nose area and you can see the three whiskers on each side.
After flattening the Mountain Dew can (whew- lots of caffeine in there) I added a cute white dog with brown spots using acrylic paints. Then I mounted it in a wooden frame.
The soft drink can was crushed, flattened and then painted with this smiling spotted dog standing in a field (waiting for someone to throw a frisbee, perhaps?). Then it was mounted in a white frame, ready to hang.