> If you arrange enough big chunks of metal into a spherical-shell constellation, then drop them all toward their mutual center, they can reach the threshold to

> If you arrange enough big chunks of metal into a spherical-shell constellation, then drop them all toward their mutual center, they can reach the threshold to become a black hole before they even start colliding. When I say "black hole itself" I imagine any combination of mass at it's center that provides enough density to form a gravitational pull that will trap light.