treebeard55
Chumono
Like Jason, I've found sheet-metal shears, a.k.a. tin snips, to be the best option in a hand tool. Be sure you have snips designed for straight cut, not left- or right-.
I've also used a soldering iron. Takes longer, but there's no cracking, and it leaves no sharp edge.
I've also used a soldering iron. Takes longer, but there's no cracking, and it leaves no sharp edge.