Zhosho made a nice Sovereign-class starship (of the Enterprise-E's sistership, the Yamato) some years ago: www.geocities.jp/ikenohata2005…
Unfortunately, the download links seem to be gone, but near the bottom of this page: www.geocities.jp/ikenohata2005… you can find his e-mail adress (just replace the [at] part with @) so maybe you can ask him if he could send you the files?
But of course, maybe you can find a different papercraft Enterprise-E on other websites too?
I'm sorry I can't help you better than this...! (
Most of them were drawn by hand, but there are a lot more papercrafters that also like Star Trek, like [link] or [link] or [link] or [link] to name but a few, and on this site: [link] you can find a lot of links, but there are *many* more! ;o)
The Voyager you made is from somebody else though, mine was drawn and painted by hand. But I think the Enterprise-D in your gallery is one of my models. It has a lot of thin parts, but you did a great job building it, it looks very good!
The more paper models you make and build, the easier it gets to visualize a flat piece of paper taking on a 3D shape.
And then with trial and error (test building) you can trim and fine-tune the parts until everything fits together the way you imagined!