As for bulk mass production, those same 3D tools can be used to 3D print molds for mass production, too.
For mass production there will be only few engineers who design molds.We could replace people picking up bottles and corking them by hand, with a machine that would automatically grab a bottle cap and stick it on top of a bottle as it went by.
I think this is already done, may be not on all factories (cost of the machine may be higher than wages for workers in case of small-scale manufacturing).Unless by "automation" you mean "artificial inteligence,"
We don't need super-human AI to automate most jobs. Even advancements in existing areas like image processing and recognition, neural networks, genetic algorithms/programming, cheap sensors and mechanical manipulators will be enough to create robots and software systems which could free 80-90% of the workers.Yes, it is. Is it really that difficult to comprehend that we didn't even know about internal combustion engines in the 1800's, or about computers in the early 1900's, or the internet in the early 1990's? Because a lot of incredibly brilliant people could not predict such technologies arising and creating tons of new specialized jobs, I am not going to trust some unknown guy on the internet making predictions that no such new technologies will come to exist in the future.
This new technological wave could be robotics and AI, who knows... 
We still have jobs that pay people to remove staples and paper clips from documents before scanning them.
Most likely we won't have paper documents in the future at all! BTW, I don't even remember when I used the paper last time.There will always be jobs, no matter how high tech we get.
Only if your govt or corporation have enough money and willingness to keep the inefficiency. This can be true for some parts of Asia, but never for Europe and US!So, instead of people working on a project for one or two years, and us buying products, like a new version of an iPhone, every one or two years, you would have new and improved products coming out every month, then every day, then pretty much continuously, whenever you have time to hit "Update."
Advertising budgets are skyrocketing even for 1-2 years cycled products, so I cannot just imagine how much funds you have to spend on ads to force customers buying new iPhone at least once per month! 