RepRap, a (potentially) self-replicating 3D printer 17 years ago
Thats already the reason for China - injection moulding is very cheap (once you have made the mould) and commodotized. It's assembling and packaging the parts that takes a lot of time/labor. It's the low labor cost of assembly that is the reason for China - a million 3d fab machines replacing a few injection moulders isn't going to change the time it takes to put the bits in boxes.