IMO you need to work on smoothing out the metal first before welding up the holes. If you can't visualize the damage and most people can't, go down to office depot and buy yourself a magnum magic marker. Take said marker and ink the entire damaged area. Now take a sanding block with say 180 grit and block the panel.
Your results will then look like this.
2003_0101Image0007 by
eric2406, on Flickr
This is hammer on dolly, it will stretch out the metal.
hammerondollypic by
eric2406, on Flickr
This is hammer off dolly. This is what I would be using to smooth out the metal. The hammer and dolly are never in direct contact so stretching is limited.
hammeroffdollypic by
eric2406, on Flickr
Kinda the basic path of dent repair.
Scan_Pic00031 by
eric2406, on Flickr
Scanned pics from the 1st edition of the Keys of metal bumping by Frank Sargent...1933 if I remember right. Pics are out of order but you can follow the page numbers.
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
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eric2406, on Flickr
Am also of the opinion that body hammers in the hand of the unskilled can cause more damage. I use a slap hammer probably 99% of the time doing dent repair. The surface area is larger, more forgiving and IMO just a superior method then a body hammer. You can make a slapper out of a old leaf spring. The slapper on left is a slapper I bought from Covell.biz many years ago, the larger slapper I made from a F250 leaf spring.
mostusedtools by
eric2406, on Flickr