Actually, the power source inside a hologram is a good idea, only add to it a powerful immiter. Take the core out of a runabout (with its M/AM tanks, and all that stuff) and slap an immiter on it. Then, if you need a ship/habitat/station, there it is. Just program in a few safe guards -ie: saying end program on a file search and watching the ship go bye-bye- also that the ship be runabout sized or bigger, to about galaxy (or what ever the immiter can handle).