Depends on the scale, but in most cases it is various pliers. For smaller scales I use small nose pliers and just put two right angle bends in. In very large scales I like a bit of a radius on the bends, so I use the needle nose pliers. This is a little more challenging, since the spacing is harder and I have to check to get the bends 90 degrees.
Sometimes if I need to make a bunch of identical ones, I use a piece of wood of the proper thickness to get the width uniform. In this case I use a softer wire, and bend around the wood with my fingers. Lots of thicknesses of basswood at hobby shop. I put the wire across the edge of the wood, and bend down on both sides with fingers, then cut to length. Also with pliers I bend with lots of extra wire on ends, then clip ends to length.