Then I went to Home Depot and bought a small sheet of steel or aluminum maybe 12" X 12". I used tin snips to cut a about of steel or aluminum inch wide and 3 inches long. With a hammer, I gave the piece of metal a slight bend by finding a solid rounded curvy shape object (like a vise)and tapping the edges and center to give it form. The form being the surface of the door, starting from the window opening and down along the crack. With the crack being in the center. Once I have the shape, I then place it firmly on the door crack. It's a good idea to smooth out the edges with a file or bench grinder. Then, I will use pop rivets: I then drill 3 to 4 holes on each side of my repair piece. I pop rivet my repair piece and voila! Steel or aluminum rivets should work.
After that I will bondo this area. Bonding is an art itself. But basically you put your first layer down, wait 24hrs to dry, sand with may 60 grit sandpaper, then 100 grit sandpaper. You will see that you have to repeat the process several times; bondo, dry, sand. On the last application of bondo and sanding, you'll want to use a wet-sand paper that is about 300 grit or so. You can find great tutorials on bondoing on www.YouTube.com.
Here's a pic after the metal repair piece has been placed, riveted and bondo
Here is where the repair piece is:
Of course you could have it done professionally: welding or put on a new door skin but most of us can't afford that.
