More than a few museums have been making their image archives freely downloadable. The Smithsonian has done them one better, posting both images and digital 3D scans that you can download as CAD files and do whatever you want with. "This includes images and data," the Institution writes, "from across the Smithsonian's 19 museums, nine research centers, libraries, archives, and the National Zoo." The total number of downloadables is nearly 3 million.
The portal for all of this is the Smithsonian Open Access website. If you're interested specifically in the 3D content and CAD files, you'll want to jump into their 3D Voyager section, where you can download scans of wonderfully random objects (a Morse-Vail telegraph key, the crew hatch of the Apollo 11 spacecraft, a letter opener from the Black Star Line), vehicles (the supersonic Bell X-1 test airplane, the Space Shuttle Discovery, the Wright Brothers' Flyer from 1903, the complete Apollo 11), furniture, statues, objects, old package designs and more.
The level of detail you can access is nuts. As one example, check out the aforementioned Bell X-1, where you can download both the 3D model and extensive documentation of the cockpit:
Nuts, no? You'd simply never be able to see up close, and pore over, this level of detail if you were at the museums in person.
Check out more 3D stuff here, or go here for the full combo of 2D and 3D files available. And thank you Smithsonian!