I recently visited the JDB factory in Shenzhen (PCBWay brand outside China):
I only visited the PCBA floor and the drilling / milling and testing parts, as the chemical processing facility is 15km away so I did not have enough time for that one.
Interesting to hear that they now get 60% of their orders from overseas.
Let me know if you have any questions or topic ideas about Electronics development in Shenzhen