I've tried to look into this, and haven't figured it out yet. I'd like to ask if what I seem to understand is correct.

3D "printing" is a puzzlement. Going through Wikipedia it seems that it is not "printing" at all, nothing to do with printing.

It seems be a process more akin to painting, where various materials are sprayed hoping to create an in place part. Not possible to be taken apart for repair or replacement.

More a robot than printer, in fact it's not a printer at all. In fact, it seems to be the opposite of machining, which takes a billet and takes off excess. 3D printing seems to be a way to build up material until the desired shape is achieved.

Both of those processes are digitally controlled.

Is this correct?