Assuming you could put the objects in proximity without leaving them in motion, any mass at all would do. Now of course there are repulsive forces from electron to electron, but assuming you've got neutrons, a pair ought to do you. You'll need tweezers. ---

I have a question concerning gravity. Suppose I could do an experiment in space. Approximately how much mass would each of two identical objects require in order that if they were placed next to each other their mutual force of gravity would hold them together.

Mike Bailey