I dunno. Given a self-supporting spherical structure around the planet, you could raise it above the atmosphere and set it up to experience a net torque from so

I dunno. Given a self-supporting spherical structure around the planet, you could raise it above the atmosphere and set it up to experience a net torque from solar radiation pressure. Just add "sails" that are black on one side and mirrored on the other. Then sit back as it very very slowly spins itself up to orbital velocity. Of course, there would be plenty of practical difficulties. (For one thing, radiation pressure is a hideously inefficient use of energy; for another, your spherical shells will be unstable and require constant maneuvering to keep them centered.) So if you have an army of self-replicating robots, it's probably easier to just have them build millions of solar-powered mass drivers and fire rocks directly into space.