Are there many assembly type 3D printers?
Yes and no:

Yes, there are machines, that assemble things from parts. For example, SMT placement equipment &amp; pick-and-place-machines. Almost all electronics are made this way. In fact, a lot of items are made by using Pick-and-Place machines in the final assembly.

On the other hand: No, there is no 3D-printer, that works by just being a P&amp;P machine: it simply is not inside the specifications of additive manufacturing to be just an assembly machine. That is an assembly or pick and place machine, no matter if they call it printing. It is not.

However, I have seen a recent makerfaire video and a talk that was showing a prototype of an E3D toolhead swapper, which - in its idea - would allow to combine a 3D printer with a P&amp;P machine. Their idea is to fully automate the manufacturing process, including adding non-printed parts with grabbers or the like.