Originally Posted by
fietsbob
Just now predominantly, most of the cogs of cassettes, are all combined in a subassembly, there are no screws to remove to make loose cogs.
that was back in the 8 speed era.
Shimano's 105 and Campy's Veloce 10-speed cassettes are all loose cogs and spacers with no subassemblies or groups. They are possibilities for customizing if you can find the desired replacement cogs or are willing to mix-and-match between two cassettes.