Can experts identify the model using this part (FOD prevention purposes)?
This is a Military Standard fuel cap, part number MS29525-1. 

Here is the DOD page for the products: MS29525-1. It is most likely from a military aircraft or some kind of private ex-military warbird.

There really isn't much to say on it, other than it is used by the Air Force and Navy, as well as some British aircraft. It is a universal part used on many different types. It is a serialized part, you could try calling a local airbase and see if you can get records for it, but they will probably not care enough to track it down.

By the way, whoever is missing it, if a private party, paid a dear price for losing it. The cost of these caps in the private market range from \$600 to \$800.