How to park a tiny part?

[Romulus]

I went to a gun show in Vallejo this weekend, hoping to find a part for my Ithaca 87 (37.) Following the advice of a master gundsmith and old friend from WI - thank you Wayne - I looked for "the old gent with a box full of crap parts" and there it was: beautiful, shiny, an impeccably checkered piece of blue steel. Beneath the old rusty trigger guards and beat up hammers and God knows what other pot-metal, I found an old fashioned magazine tube cap for the Ithaca (the newer caps are quite awful)

Problem lies with the blue: I need to parkerize this little marvel to match the rest of the shotgun. I am soliciting advice from you folks on the best and cheapest way to go about this...

Thanks