It's very hard to make heavier elements (anti or otherwise) out of lighter ones.!
Except for making helium out of hydrogen, humans aren't capable of doing this.
I believe that you could fuse anti-hydrogen into anti-helium using the same methods as we do normal fusion. But it would be harder because of all of the containment issues.
Forget about making anti-iron any time soon (or iron, for that matter). Hope we find an anti-asteroid for that.