Asteroid use

MW: The difference between building structures in
space and building structures on Mars is that on Mars
you can live off the land. There is soil and carbon,
hydrogen, nitrogen, and chlorine on Mars but all of
these have to be imported for a large space facility.
And Mars will probably export these chemicals to the
moon for the lunar industries. The industrialization
of the Moon and Mars are the first steps towards the
future affordible construction of space islands, IMO.