Boil Kettle

I would like to have some advise on how to build a boil kettle. I would like to be able to run 5 to 10 gall. of beer. What would be good to make it out of? I know a lot of people use a sankey keg but what if I couldn't find one. What else could I use? I want to make it myself. What are some other thing that I need to think about? Any information would help.
Thanks
David

Go to used (or new, but it will cost more) restaurant supply store. Buy a big pot. Done.
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Alternatively, mine some ore, smelt it, cast it.
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Alternatively, buy some sheet metal and a hammer, and hammer yourself a pot.
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Alternatively, buy some sheet metal and a large press, and press yourself a pot. Have fun grinding the dies.
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Alternatively, buy some sheet metal and a welder, and weld yourself a pot. Remember to passivate the welds, and do a good job so they don't leak.
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Alternatively, cut an old whiskey barrel in half, and brew by dropping hot rocks into it. Or cut down a white oak tree and make the barrel, first.