Pre-Rama

Carrying on from Rama: if we start with an asteroid already in Near Earth (or Venus) Orbit, we can work with it before we go full Starcross. Deimos is in our range although it might be difficult to Rama this at the same time we're attaching a tether. But there's plenty like it out there, for instance Mars-crossing 1036 Ganymed.

The miners send robots to burrow in from outside. The robots, once they've carved out sufficient space (and maybe done some mining of their own) fuse seals upon the more-promising tunnels. Someone spins the rock along its longer axis - not much, just to 10 ms^-2 (I call it 10 g; just slightly heavier than Earth surface) on the outside. At first we would also have to counteract the gravity of the rock itself, but again, that won't be much. Now the human miners can run in, pump nitrogen/oxygen, and do what they do best, in Earthlike gravity and atmo.

But really our aim isn't the rock's wealth; it's the rock itself. We're aiming to make this rock an O'Neill (Reagan subset): as cylindric as possible. So the miners should concentrate on the widest part of the spin, and push the slag off to the sides. Eventually they work up toward the axis.

Also when the spin is high enough, we start to carve out that 1 km radius empty hole through the axis, on either end. These deep low-G craters will be a safer spot for incoming ships to dock, rather than the quickly-spinning and now over 10 g outer rim. These docking craters are still airless at this stage.

Once there is sufficient worthless stone between the outside and what the miners're mining, the big rock can be spun up that bit more, so that the 10 g point is further inward.

Best to push the big rock around when its innards aren't fragile; when the asteroid isn't hollow-world yet. For given values of outer silica shield: that's when you decide the Rama is ready to be moved into Earth-Moon Libration, or into Earth-Solar, or even to Venus-Solar.