3D Models
In my line of work, I use a LOT of 3D models, and of course, I want to pay for as few of them as possible.
3D Cafe has a section to the right called "Free Stuff." Click on that, and there's quite a lot of models, many in good old DXF format. You might find something you can use.
Interestingly, almost any SF spacecraft or object you can think of is available as a 3D model from some enthusiastic fan.
As for paper space, I've never tried adding text or anything that crosses viewport boundaries, so it's never come up.