I first started following the field of 3D printing around 1999. Subsequently as printed electronics formed, I took an interest in both areas.
Each year I used to write reports on the subject, though I haven't updated any of this since 2007
For reference, I've linked to an old report (2006) on the subject. It's completely out of date but the concepts are still probably valid. Don't expect any insights though, this stuff is widely known today.
For those completely new to the subject, it might provide some very generalist background info. However, be warned, being so old the industry is likely to have changed significantly.
Back around 2004, I came across something which I thought was truly dangerous for this future world. Unsurprisingly it's a patent but this patent is for the equivalent of soldering in the future manufacturing processes.