Re: Shuttlecraft - curved edges on top?
The full-size mock-up had a simpler bottom side than the miniature because, of course, it would never be seen onscreen. What you see above is the full-size mock-up with just a few of the miniature's details adapted into it to make it a more integrated design. The most notable detail of the miniature was its more distinctive underside which could have been shown onscreen if they had chosen to do so.
STAR TREK: 1964-1991, 2013-?