It isnt easy when you have 9 doors to choose from and they all have some issues.   The driver door I have chosen because of its straightness and the fact I have the tools to fix rust and not the correct tools (and knowledge) to fix bent doors.  This door is in great need of the inner and outer bottom 6" and only simple work on the end structures. 

I started by cutting the inner structure out at the bottom.  I cut a straight line across at the point where I got the best metal to weld to.  I did not have to worry about jigging the door first since the rest of the door is sound and the side structure is very strong and held by the rest of the door.

 

Using best guess measurements from other doors I was able to bend up a panel for a blank to make my inner panel from.  Bending this panel was only possible because I had access (at work) to a metal brake almost capable of doing the bends.  One of the bends was too close to another and so the panel I made is not quite right, but it is close enough.  After I got the bent panel trimmed to fit in the hole I marked the step edge (I dont know what to call it) to make it fit into the existing structure.  The shaping was made using hammer, dolly and a vice.  As a rarity I have set it up to do an overlap weld, but this area is not seen and the extra strength wont hurt.

This inner panel still needs to have a curved flange made.  I made up some dies for a bead roller I got at a garage sale (so cheap I almost hurt myself getting the money out) to try out some techniques I saw some other people using on the web.  One simple way of making the curved flange is to make a hardwood pattern and clamp the metal to it and hammer to form.  The hammer method works very good and is pretty simple.  What I did worked ok, but I think it would work better with the right die setup.

The idea is to start a bend in the metal and use a hammer to continue it around.  This did leave me with a flange exactly where I wanted it and following the curve I wanted.  I was thinking I could get a much cleaner and deeper tip, but I think it might be I made the diameter too small.  If anyone knows more please tell me.

The outer panel I am welding in is my third version.  The first 2 I tried to make with perfect cuts and bends and tipping with the tooling I made.  I found out I am not good enough to make it all work on the first try so I roughed it out a first then trimmed it right.  I used 2 pieces of angle iron in the vise to make the 90 degree bends for eventually folding over the inner door structure.  I first put my rough chunk of sheet metal on the door and scribed the edges so I have the angles correct.  I notched the corners to 45 degrees and then bent to 90 degrees the bottom of the patch panel.  I then bent one side edge to 90 just outside the scribe line.  The next is the critical for proper fit.  I put the panel on the door and set up the opposite side bend to match the bend on the door and bent that to 90. 

Using an arbor press and die I made up I pressed the bead into the lower portion of the patch panel.  I used the 90 flange of the patch panel to keep the bead straight.  Once the bead is in place I bent the lower flange around using a hammer so it will fit loosely on the inner structure.  Then I was able to use a very expensive tool (my hand) to arc the whole panel to match the curve of the door.  This is actually delicate work as it is easy to over bend and warp the panel beyond use. 

All that is left now is some cutting and trimming to make it ready to weld in.  I still need to replace a pitted section just below the lower hinge.  That was just a rectangle that needed to be carefully welded in place.  I currently use a mig welder (Lincoln SP-175 I think with gas) and use the spot technique to put the panels in with the least amount of heat.  I really wish I had a TIG, but that will have to wait.