SamTherapy covers this very well in his comment above. As far as 3D content goes, If it is a work that is a derivative of another work, such as movies, TV, another artist or a book, it CANNOT be used for any commercial work. Period. That means any 3D content for sale based on a movie or game, or whatnot is a violation of copyright. It also means artwork made with those assets and likenesses cannot be sold or used for any commercial purpose. The only way around this is to acquire a license from the license holder. A non commercial license means fan art can be created, but it cannot be sold.