Recent experiments regarding Quantum gravity, Gauge Theory, and M-theory all point to gravity being a lot closer to Magnetism than we've though. It's just that in 7- or 11-D space/time, only one part of gravity "extends" into Einsteinian 4-D space/time with 3 or 4 other dimensions its effects extends through. If a couple of these experiments shake out the way I think they will, then gravity is just another force like electro/magnetism and can be generated, shielded against, and go through all the other energy state transformations that all other types of energy do.
This means control of inertia as well. Without inertia, Light speed, relative to local space/time reference frame, is entirely possible without violating General Relativity. Special Relativity is already on shaky ground and even Newton didn't want to theorize as to what actually causes gravity.
No schoolboy has missed the comparison between gravity and magnetism. Certainly it didn't take long for science fiction to jump onto the idea of electro-gravitic energy.
This is one area where science has had difficulty catching up to science fiction, however.
Since ferromagnetic materials can generate and respond to magnetic energy, I'm inclined to think that certain elements, when excited in specific ways, may be able to generate gravitic energy.
What it would take to get the atomic elements lined up and lasing gravity waves is another question. Perhaps an ordinary laser is doing the job of lining up the atoms, but we need to step up the energy input to the atomic structure to get the atomic response, as opposed to merely an electronic one.
Pounding "Dilithium" or whatever, with cosmic ray energy, or Beta rays, for example, might do it, but who has made this experimental setup?
Atomic nucei have many modes of vibration. Electrons can only bounce. It could be that a particular mode of vibration, of a particular class of atomic nuclei, does produce the effect we want to develop.
Other than thermally, how does one excite an atomic nucleus? I am intuitively convinced the secret would lie in that, because I don't think there's anything we haven't done to electrons.