Your going to need away to shrink metal.I use a stump primarily for shrinking,a cheap hammer you can make is a baseball bat hammer.A sandbag for streching can be made from an old purse.Some post dollys can be made from some odd shaped pieces of metal.
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This was my first set of tools
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You can make a slapper from a old leaf spring
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post dollys can be made from scrap you have laying around.
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here is a baseball bat hammer
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This is my stump learn how to use it you can really shrink a panel.
There are methods we use for welding,patterns are also important.Try to read up them.