I let my dad cut it with a torch. That guy can keep a perfectly straight line in a round piece of steel on the coldest day in February without even putting his glasses on (yesterday). He worked in a welding shop all through highschool and he still hasn't lost the touch (he's over 50 now). I'm ok with a torch, but I would've had to grind a few burrs here and there; when he was finished it was the smoothest torch line you can imagine. You can run your bare finger around the edge and not worry about cuts and snags.
I live 3 hours away from him so I'll just have to work on this whenever I go to visit but I'm hoping to get it done in the next month or so. Yesterday we got the lid done and threw the barrel and lid onto a big brush pile that we were burning (after it had burned down a little). I will be ordering 2 Weber 22.5" cooking grates off amazon, and should be able to get the finishing touches on it next weekend and maybe actually cook on it in a few weeks.
Sorry, I tend to ramble on...
About the lid, we cut the barrel just above the bottom rib (leaving the entire rib attached to the bottom third of the barrel). We took the bottom and set it on the floor and used a hammer to bend the edge over onto itself to give a nice clean look. So now you have part of a barrel that has a "flare" with the edge rolled over. We discovered that this was a bit too tight to fit on the drum properly. So seeing a challenge, we went forth to try something. Worse case scenario we would've had to get another barrel from behind the barn (lots of them back there).
This will create a perfect "lip" like on a real grill/smoker lid (like the Weber's). We then hammered the flare out flat so that it would set down perfectly flat on top of the barrel (with a flat "flange" sticking out the sides).
Because I had already cut the head out of the smoker drum, we used the bottom of the smoker drum to do the next step (for rigidity) but if you leave the head in the smoker drum for this step it would be best.
Set the lid on the full barrel and center it, then have somebody sit/lay across it to hold it firmly in place (dad laid on it while I pounded on it). You have a large flat rim that sticks out at the edges. Lightly begin to hammer this edge down. Go really lightly and alternate sides until the lip is bent down enough to hold the lid centered. Don't let your help get off the lid yet, it still needs held in place. Don't be afraid to stop and check to be sure its cented while doing this; once you get too far into this part its hard to go back. We did get one little part that didn't form properly but it is good enough to work. Continue hammering this lip down, slowly working your way around the drum, little by little, until the lip is hammered all the way down and up against the top lip of the drum. You've now created an offset lip. The lid will go down and the lip will seat around the outside edge of the drum, while the should of the lip will set on top of the drum.
Do you follow what I'm saying? Its pretty complicated, but if you have the tools/patience, and you want a challenge I think it makes a fantastic lid.
I'll have to get some pictures up, but unfortunately I was in a hurry to leave my parents house and get back to mine before a snow storm yesterday and I didn't get a chance to take a picture of the final product lid. Maybe next week.
If the offset lip seems like too much of a challenge I did see another post on here where somebody used the bottom third of a barrel and rather than roll the upper half of the rib onto the lower half like I did, they hammered it out to form a large lip that seat well over the edge of the drum. This would likely be much easier, but not quite as clean/nice looking IMHO.