The beginning will come from our world. Evolutionary creatures through the various stages of life....until we create the inanimate and keep it alive. Finally, they can create or spread their own species by themselves.
No matter if it's expanded by pregnant or factory. It up to the evolution that will bring it to where.
Why do we have to build them up?......Because we have 9 planets, but our world is the only place that has an ecosystems and organism....we have age, sick, deterioration and die....This is an our disadvantage.
Finally, time and evolution will be made us create something to live, such as robots.....The robots will be alive on this earth and other planets....and represent us to find new sources of energy, elements beyond the periodic table, new medicine, tourism location etc
They have the advantage of longevity, not sickness or illness, withstand the environment.They can build a city and stay on that planets....There would be have both human ai that have free life like human and the robots that must have controlled or remoted from our world.