I would say you can be what you want, it just depends if you are good or not. With freedom of expression, you can build a lego castle and call yourself an engineer. But are you good? Do you have the requirements to be one?
And like others have said. Blacksmiths don't really have degrees to be considered a registered blacksmith (to my knowledge). You can call yourself a writer, but can you write well? You can call yourself an artist, but can you draw well? So I can say confidently that you can call yourself what you want, it is just whether you are good or not.