Answered
2 questions:
1. In the 3d annotation's context menu there is a "set to fullscreen" function. Is there a also a way to display a 3d annotation in fullscreen mode by scripting?
2. Is there a way to print only the 3d annotation, maybe with the JavaScript PrintParams object? I have a pdf page with an embed 3d annotation and two flash applications. Unfortunately the flash apps are printed also, but I don't need them on printed paper. ;-)
The best thing for me would be a printed 3d scene in fullscreen mode.
2) You can't print just a section of a page with scripting nor access the print function while in full-screen mode, but you can prevent other objects from appearing on printouts either by moving them onto a non-printing layer (to do that to rich media you'll need a plugin) or by adding a watermark layer over the top of the page (white but with transparent "holes" for the printable regions), then set the watermark to be visible only on printouts.