You have made two threads about this, yet in neither are you clear as to what you want to do.

Why not just continue your original thread, instead of making a new one?

Anyway, you use a ship with a constructor module to create a station. It can be an influence station, an economic station or a military station. Then you can send additional constructors to upgrade the starbase with modules that you have gained through researching certain techs.

If that does not answer your question, then please make your question more clear as to what you want to accomplish.

He wants to creat a custom-player designed-SB, which is unfortunatly impossible.

You could MOD some SB fetures, but they would be for every civ.

Um, you can have individual Star bases for races, just make it require a unique tech that only one race has access to. This requires editing the star base file with notepad, since theirs no editor for it.(It honestly not that hard, just copy and paste an existing one to the bottom, making the necessary changes to names, requirements, and abilities) Unless he meant a custom star base model(graphic), which you would have to create with some 3d imaging software I'd imagine..