With the internals installed, now it's time to clean up the wreckage. First, grind the area to bare metal. | 
When making a template to fill the elongated hole, the easiest way is to place a sheet of paper against the door and trace the outline of the hole with your finger. The mark will be imprinted on the paper. | 
As for the other hole, I simply placed a sheet of paper behind the hole and outlined it on the paper. Remember, on this type of template you want to cut to the outside edge of your line for a tight fit. |
The sheetmetal on the door where the patches need to be welded in is curved. To accommodate the curve in my patch, I found a round object to bend my 20-gauge cold-rolled steel. | 
From there I traced my templates onto the curved metal and cut them out with a pair of tin snips. | 
With the patterns cut, I test-fitted them and made several small trims to get them to fit just right. |
Next up, I welded them in, bouncing around the patch to keep the heat down. | 
I also cooled each stitch weld with air to keep the temperature of the metal down to avoid warping. | 
Note to self: a good way to weld your patch in as flush as possible is to tack it in one spot, push or pull the metal with a screwdriver or body hammer where you want it, and tack it in each spot. Once the piece is adjusted accordingly, weld it in fully. |
Along with the two big openings, there are two holes about a quarter-inch in diameter. Instead of welding in a piece of metal, I decided to fill the hole with weld. But before I did that, I took a screwdriver and cleaned the paint off the inside of the hole. That way, the paint won't contaminate my weld. | 
Lastly, the welds were ground down. Now all it needs is a skim of filler. | |