I assume you are looking at more than just a sling for your project. I am away from my American reference sources for about a week. The History of American Sailing Ships and my book on Baltimore Clippers by Howard Irving Chapelle are what I want to see. For now, I do not believe chain would be in use in 1812 for either the Bobstays or Shrouds, nor do I know of any rigging that uses iron bands to secure eyes to the bowsprit yard at this time in the Royal Navy or continental powers. Online poor resolution plans show one gammon and two bobstays (vs. 3).
It will be critical to determine which rigging needs dead eyes, hearts and/or thimbles/eyes. Seizing also adds a lot to the look. The fun part is the foremast and mainmast stay blocking!