Not a lawyer either, but:

> What if I take the design, print it, include the thing in a staged photo, and sell prints of the photo?

Probably fair use, provided the design wasn't the main focus of the photo, but merely part of the "set dressing."

> What if I skip the printing and use the design files as a basis for a rendered photo or animation?

> What if I print the design, then use a 3D scanner to recreate a file from the physical artifact?

Those questions are simpler - both scenarios would be derivative works of the original files, so covered by the license.