Ookkey, this is embarassing to say the least but here goes:

I magine you have an assembly, where you've modelled a tringle, a square and a circle. The assembly file is those three items. They are all drawn in the assembly, not separate files.

Lets say i want to save the square in a separate file. Ive gone as far as move/copy the part and its now floating above my "assembly" ready to be deleted when no longer needed.

How do i save that single part, to a new file?