"... So you are saying I should spot weld the pan and the body together? That sounds good. "

(giggle, giggle) No, but it might be a good idea; I haven't given the idea much more than incidental thought so I am not sure about that. When dealing with glass buggies that isn't a fix available

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It might stop some other problems such as bolts loosening up and rust problems though but again, maybe not either. Mr. Porsche wasn't the first it was the 1922 Lancia Lambda (
http://www.curbsideclassic.com/automoti ... odern-car/). The Germans were well a head of the rest of the world in working metal; take the German military helmet used in WWI and WWII and compare it to the English and American "pop tops" of the same era. They were able to do (what turned out to be 2-step forming as I remember) "deep draw forming" well ahead of the rest of the world. I've mentioned spherical radius several times before quite a few times but I am not too sure if I talked about "radius tear out" during deep draw forming or even shallow three wall joins such as the rear of the pan... but I digress.
I forgot to mention that instead of doublers supporting a hole you can also flange the hole for additional strength instead. It works similar to bead forming for flat metal. There are hole flanging kits available ($$$
https://www.bing.com/images/search?q=ho ... &FORM=IGRE for example) that allow you to use a male and female draw-through kit using a supplied bolt. I have seen them in use (video/film) so I know they work on thinner materials but I don't know of any oval shaped hole available (see below) and material thickness limitations. Lightening holes, in thicker material, would be a similar but not the same for example but in thinner materials the length of the strengthening flange beyond the hole's radius is important.
There is a "standard" for the flanged slots but it has been so long since I designed to one I forget where the standard(s) are as far as a fed standard goes(
https://www.bing.com/videos/search?q=sl ... &FORM=VDRE for instance). Close hammer and dolly work might work if done incrementally and slowly but there has to be a size limitations also.
As I said, working metal is comparatively easy, working it correctly can be very time consuming even if you know the rules.

One of the reasons I try to interject some of what I learned from when I was designing/drafting parts that required forming... I had to be taught or learn how to research the rules also... kind of like potty training

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