on the other hand, i'd say just keep working at it.  sure there are lots of things people haven't made, but a lot haven't been made because they're not typically something you'd use.  don't avoid making what you want to make because someone's done it before.  and we all learn from each others' work.  just don't make that your only reference.  always have the real thing as your primary reference. if you have a helmet based on that person's work, get images of helmets (or a real helmet, if you feel so inclined), and add your own improvements and changes.  apply what you've learned to your own vision.