There have been several articles on a liquid metal robot based on a single paper. This is that paper. It's about using microwaves on an easily meltable metal and how it can be reformed using magnets. That's not the T-1000, but it could help with 3D printing by making a base for the shape and then melt away.
Plasma thrusters are more powerful than they seem. A team was able to get a small thruster to emit the same power as a larger one.
Replicators make a base form and then fill in the areas with specific materials, while a 3D printer uses a layering system. The ability to design the object would be the same, but how it is made would be different. I think this desire to keep going is being bolstered by 3D printers, and hope newer ideas and methods move us forward.
The liquid metal idea may be a step in the right direction.