how do you convert energy into mass??

it should be able to exploit this to create "artificial gravity" right?

like if you had an accelerator that created millions of micro black holes then they would evaporate immediately wouldnt that impose a gravitational field around the accelerator?

what other ways could we accomplish this and is the black hole idea even feasible?? Hawking said that we would have to use all the energy in all of the deuterium in the ocean to create just one black hole? Was he wrong??

Could we smash particles into each other to create something like neutronian for brief instances?? What quantum field would we exploit?

Is it possible to use photons and the energy associated with them to create electrons?