I am a cooper, and the things you need to make a barrel are metal rings, a fire, wood planks, a hammer, and a tape measure.  To make it, you take some wood planks and a ring and put the wood inside the ring.  Then you take the hammer and use it to hit the ring down, but not all the way down.  Next, you put the barrel down so the fire is inside the barrel.  Third, it will help it to bend, and then you make the wood tight together and put the bottom ring on.  That is what a cooper does.