If you are making the initial cut, the sawsall will do a nice job. Just draw it out well beforehand where you will cut, put some masking tape on before you draw if you want a good edge. But it is not necessary since you will fold that edge anyway. If you make a lot of little cuts about 1" aprat where you will fold, you can then just use a crescent wrench to make the fold with. Much easier to fold that way, then touch up with light hammer.