Like, is the mass required for a self-sustaining interstellar generation ship, with all the required shielding needed to handle high-velocity interstellar travel (blasting through the interstellar medium an appreciable fraction of c means absorbing a crapload of high-energy particles, and the occasional micrometeorite that can't be detected until it's too late that hits the ship with the energy).

For example, hitting a little 10 gram rock at 0.1C would be a kinetic energy transfer in the gigajoules - like a small (1 kiloton) nuke.

So we've established our ship needs to have armor that's thick as hell. In order to make that economical, it must be huge. Also, in order for it to do useful work there, it needs to contain factories worth of machinery.

The sheer scale of this ship would be staggering. And then that raises the question: is there enough energy available to propel such a thing?