I don’t know too much about this process myself.
My thinking is that “3D Printing” is probably not a good choice. A specific 3D Printer might be an OK choice if you concentrate on the that innovation and not on the broader technology. What do you others think?
I tend to agree with George. The focus is in the data; data input, data processing, and data output. I would encourage the student to continue doing research on how 3D printer technology is impacting non traditional 3D fields. I think there is possibly a good topic here, but it needs more, a lot more.
I have seen articles about how 3D printing technology has inspired a company in Austin Texas to build houses out of liquid cement. Homes built this way can be built very inexpensively and can have a broader impact on society.
Combined with laser scanning, doctors can make casts to fit the patient quickly and precisely. If the student will explore beyond “3D Printing”, it may work. Have the student compare her idea to the Explore Scoring rubric.
3D printing by itself would not be a good choice as an innovation. I think @randle.moore makes a good point about the areas where 3D printing is making an impact. I attended a creative conference session where the presenters were changing lives with 3D printed arms with sensors that gave physically disabled children new limbs. The children could operate the arm and fingers with their existing muscles. A topic with that depth may earn your student a good score.