zSpace

A huge PDF list of free 3D model resources from the staff of the ELAArea Public Library in Illinois.

"...Here you'll find a growing collection of 3D models, textures, and images from inside NASA. All of these resources are free to download and use. Please read the Usage Guidelines."

National Institutes of Health 3D Print Exchange.
"Few scientific 3D-printable models are available online, and the expertise required to generate and validate such models remains a barrier. The NIH 3D Print Exchange eliminates this gap with an open, comprehensive, and interactive website for searching, browsing, downloading, and sharing biomedical 3D print files, modeling tutorials, and educational material."

"Welcome to Smithsonian Open Access, where you can download, share, and reuse millions of the Smithsonian’s images—right now, without asking. With new platforms and tools, you have easier access to nearly 3 million 2D and 3D digital items from our collections—with many more to come. This includes images and data from across the Smithsonian’s 19 museums, nine research centers, libraries, archives, and the National Zoo." Be sure to check their Terms of Use.

Works with zSpace