His sense of amazement about everything he shows is exactly like every science teacher I've ever had. I feel like I've been really lucky to have science promoted to me in my life by people with such a wonderful perspective.

You can print plastic or bio matter, but printing hardened materials like steel or even carbon fiber is not even on the radar yet.

Thinking that you would be able to print anything you need if you only had the materials is likely impossible.

It is like dreaming that everyone could have their own nuclear reactor in their house so that they wouldn't have to pay the electric company for power anymore.

Yes, that was a thing in the 60's when no-one understood much about nuclear energy. Just like that technology, something better and safer will likely come around that will supplant the need for that crazy idea.