slitting and welding is to be used as the last resort. study up on the metal working forums. And the FREE utube video's . get a tree stump and hollow it out, learn how to stretch the center, learn how to tuck shrink the edges. use the E wheel to smoothe things out. I went to a Covell 2 day metal shaping class. I was amazed how rough the blank looked when he first started forming it. I had always tried to work slowley into the final shape, Covell just really beat into a rough shape quickly with a shot bag and hammer then he ran it thru the E wheel and he smoothed it out. find an old bowling ball to use for a shaping dolly. A set of home made thumb nail dies in a home made power hammer fixed stroke machine can really speed things up for shrinking . you can roll your metal using a piece of pipe,or a welding bottle, clamp between 2 X 4's Etc.