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.