Great ideas.....all we need to do is find a source of
energy that is compact enough, robust enough and reliable
enough to allow such activities. To date we don’t have
that. In addition “3D printing” can make a number of
useful items, not everthing needed, especially those made
from hi strength, tempered metals but many. The trick of
course is that those printers need a source of material
to work with. Might as well haul the finished product
into space since the you’d have to haul the same weight in
material along and THEN print out what you want.
If...and that’s a BIG if, we can successfully find a way
to land on and mine asteroids the issue of raw material
will become much less a problem.
My idea for asteroids and comets is to redirect their orbits to collide with Mars.
This is a terra forming idea. Mars bigget flaw as I see it is that it lacks a magnetosphere and gravity strong enough to hold an atmosphere dense enough for human habitation.
If we bombard Mars with enough asteroids and comets we will add enough mass, gases and water to make it habitable. The added benefit being that we are ridding the neighborhood of NEOs.
It may take a million years unless we come across a really large nickel-iron asteroid and a big comet to drop on Mars but do we have anything better to do with asteroids, comets and Mars?