I use a dremel. It is a rotary cutting tool. It works great for cutting most metal, even though the actual cutting blades wear down easily. They are very cheap though. If I have long straight lines to cut, I use a jigsaw. You can do most kinds of cutting and make the cuts look nice if you have the following:
a dremel w/ a flex shaft
a jigsaw
a file
sandpaper
Of course plasma cutters are preferable
.
-Kevin