Mining a Sphere World

[bbq]

Hmmm, isn't mining a Sphere World kinda like us digging a hole in the basement of our houses for buried treasures? In this case when you dig through the Gravity Platings you are gonna wear a hole in the ground and get empty space beyond. So...I don't understand how we can build mines on our Sphere Worlds. Afterall, there was nothing there before and I made the whole world, so where did those extra minerals come from?

Also, I'm curious to know if any of you think the building cost for a Ring World Placement component should be *different* than a Sphere World Placement? Like, perhaps cheaper in terms of resources?