I have just shipped a brigade of Engineers to a colony planet that has the components of a pre-fab PDC, as well as nine Alien (Precursor?) dig sites. How do I get the Engineers to assemble the PDC or dig up the Precursor sites? Will they do it automatically?
The digging up goes automaticaly.
To assemble the PDC, go to "industry", select "assemble PDC" and order the PDC assembled. The engineers work as if they were factories.
Note: There was a bug, that engineers would not start producing without at least a single construction factory present. I don´t know if this is still the case, as I am still on 5.20.
If it is, the work around would be to SM-in a single factory and SM-out it after the work has been finished.