Do you have access to tools to do metal machining ? it seems like probably a requirement to have such access and skill to use them..
Otherwise, there are places online you can order plates of this sort from (after submitting vector images of their layouts or whatnought), which might be easier if you dont know what youre doing.f
You could get it laser cut somewhere. Ponoko can do acrylic and maybe steel for instance.
depending on your city, there may be convenient ish hack/maker spaces who might have the tools to do such a thing, as well as people who know how to use them and could help you.
Of coures not all are really easy to get into (or cheap to get into) but it might be worth a lookaround.