In gun building, there are Contemporary and Traditional categories, and there are three separate categories within those two main venues: Apprentice, Journeyman, and Master.
If you have made a copy of an original, enter the Traditional. if it's a loose interpretation or a fantasy gun, choose Contemporary.
Never entered before? go 'apprentice'.
If you've won a blue ribbon in apprentice, you must go as 'journeyman'.
If you have blued in Journey, you must enter Master.
There is descriptive literature at the desk, and I think a poster or two to help guide you on your way.
Good luck to you!
Acer