The construction of such large habitats will not be economical if based on Earth. Such construction will have to be accomplished in space, preferably by automated processes. A fabrication unit, capable of operating from solar power, builds tools that build the tools that build the habitat shell, as well as new fabrication units, to travel to other raw material sources. Thus a geometric progression of habitat manufacture can proceed. The benefits of colonizing outside of the gravity well of a planetary body are: