To be fair, where did the 400+ planets come from? One must surely be able to import some material as well. Most of the mass in a generic system should be in th

To be fair, where did the 400+ planets come from? One must surely be able to import some material as well. Most of the mass in a generic system should be in the planets, if I remember correctly from an old article here in Sol if we scrapped all the planets we could create a 3m thick Dyson shell. But a ring should be a lot easier to construct.