not sure if anyone is shaping their own aluminum for skins / patches / etc. But I have recently joined the metal working forum ALLMETALSHAPING.COM
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Found the forum to be much like this one, packed with a lot of knowledgable people who are very helpful and who take it very seriously, but welcome newbies.
that the forum is not for frame kind of work or structural stuff necessarily, its specifically for the working (stretching, shrinking, shaping) of metals (aluminum in our case