1) clamp tin to workbench to keep it from moving around while sanding.
2) if your piece does not have any dents or dings, skip this part. unless there is
   serious damage this process will work. put the bigger piece of floor tile on the
   underside of the dent, ding, crease or whatever. put the narrow piece on the dent,
   hit with hammer until flat.  this may take some effortb to get the hang of it.
  I have been doing this for forty years so it comes easy to me. As long as the two
  pieces of tile are sandwiching the tin, the tin will not over stretch. Repeat on
  all damage until mthe tin is reasonably flat.
3) No dings or dents, skip this part also. Use the ocillating sander to remove most
   of the graphics, most importantly on the areas that were dented. I usually
   flatten out the retainer slots so they don't interfere with the sanding. Mix
   about a tablespoon of bondo, make it pink as in the picture. too light and it
   will not cure, too dark will make it cure too fast. Just right and you will have
   about 3 - 4 minutes to work it before it starts to cure. Use the small spreader
   and smooth out the bondo, you want it to be very thin, just a bit more than
   neeeded to level out the tin.As soon as it starts to cure, stop. Give it a
   couple of minutes until it is hard and the surface is just a little tacky.
   If you need more, repeat.When it looks like pic 4 take the stanley rasp and
   level out the bondo, again, this has a learning curve, if you remove too much,
   you can add more bondo. You can bypass this if you want and go straight to
   sanding. Use the sanding block with 36 g or 40 g to level the bondo out most
   of the way. then use 80 g or 100 g to go a bit further. Now you should be
   able to see any low spots, make a mental note of where they are. Mask off
   any areas that are not getting redone, usually the middle building. Get the
   primer filler and shake it really well. Spray several heavy coats then let
   it dry for at least 30 min.  Get a tube of spot putty from most any parts store
   and with the small spreader, lay a coat of it on top of the primer. Should
   look like pic 10. Let dry for at least 30 min. Sand with 220 or 320 wet dry
   sandpaper on the sanding block with liberal amount of water.  On small areas
   like these, I use windex instead of water because as I sand I can wipe the
   sanded area with a paper towel and see how it is coming along. Sand until
   the surface is level and scratches are filled. Prime it and do it again if
   needed, which it almost always is. Repeat this whole process at the other
   end as neccessary.
   4) Sand with 600 grit wet/dry wet until surface is smooth and scratch free,
   this needs to be done on areas that didn't have dents or dings also. Recover
   the slot retainers by pushing them into their original positions ( see pic 15,
   I made a tool for this by grinding a small wood chisel to the shape and size of
   the slots) and or cleaning any spot putty or bondo from the slots. mask it again
   on both sides. Spray a lite mist coat of primer to cover any bare metal and make
   an even coat. let dry overnight.
   5) if everything went as planned it should be ready for paint which is the
   next lesson.