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

This is probably acceptable

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

This is probably NOT acceptable

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

If you used that for personal things yes that would be acceptable. I do not think that would give you the right to then sell that as a product neither digitally nor phsically