Just to add to the issue of "custom models made by other people" like the Jedi models:
Public Access, as halkun put it, is the right of the user to use the file for the purpose that it was made.
IE: If it was a JK model, it can be used in JK. This does not mean there is permission to use it elsewhere.
For instance, look at gamefaqs guides, most of them are public access, but have a rule: "This file is to be displayed only on GameFAQs, and legal issues may result if it is discovered on any other site without express permission."
Public Domain means a file can be used in any form for any reason(provided it isn't used for illegal actions, such as blackmail, murder, etc.)
If, for instance, a song is public domain, it can be used as many times in as many ways as liked by the user. It could be placed in movies, on the radio, games, etc.
By default any file created (that doesn't violate a previous copyright) is copyrighted to the creator. This means that unless the author specifically states it may be used in a certain way, it is not meant to be used that way.
If I draw a picture of my character and leave it in the open on a website, that picture is still illegal to be used without my permission. (If I don't put any act of protection on it, it may or may not hold up in court, but it is still considered illegal.)
I'm not arguing with anyone, I am just trying to better explain the effect of the laws, to better exemplify what halkun is saying.(not that he needs it, I just like to keep all things clear)