Sounds from what you're saying like ground troops at that; could be entirely incorrect... have you even built them, pray tell, to check what they are?
They might be the equivalent of armored personnel carriers for amphibious operations; still, not sure, but they do sound most potent.
Maybe they're akin to the envoy units for all I know; those guys seem to have their own vessels, and are quite potent... maybe that's the case, not unlike Locutus's cube in "The Best of Both Worlds" at that.
I really do wish you luck, as beyond this, I haven't any idea; but please do provide feedback one way or the other about your experiments in this game.

I did a recent playthrough and from what I can tell, they are referring to a special event that the Borg get at (seemingly) random times that allow you to "build" a assimilation cube (Really just an event that takes resources) and there is a chance the target race's (Usually the Fed in my experience) homeworld will be assimilated and you will be immediately pulled into a war. Also the actual Cube from the event is not something you get to keep after assimilation of the world, Its almost entirely an event based object. Only use them once you are prepared (There will always be an option to postpone it). In not sure the exact triggers for the event, but this is the most I know about it, the events just triggered in the mid-late game, around the historical dates of TNG and the Borg sending a cube to Sector 001.

Ah, that makes a lot of sense as far as a possible solution to the problem of how to build it.
Sounds like a colony ship equlivalent for them then. Is that what you think too, Saint Rubicon, a Borg Colony Ship? Or their rendition thereof?
This'd be a useful explanation.

Originally posted by jamcarmody:

Ah, that makes a lot of sense as far as a possible solution to the problem of how to build it.
Sounds like a colony ship equlivalent for them then. Is that what you think too, Saint Rubicon, a Borg Colony Ship? Or their rendition thereof?
This'd be a useful explanation.

Very much in a sense. But its very much event driven, as colony ships are disabled for the borg (even for unicomplexes which is dumb, but modding is hard). I have tried many times to see the actual assimilation cube in action, but I missed both times, so I assume its just event driven and possibly has flags that check the fleet power in the main system of the target to destroy it (or maybe its just chance based). So think less of it as an actual unit that moves through the galaxy and more of an event that fires a war if completed (and a new planet thats immediately un-useful as it gets bombed to ♥♥♥♥ in the first few months).

That actually makes a lot of sense, and the Borg would use that kind of colony ship, as they conquer colonies, not build them... pity that, for they are among the most amazingly able to survive in random habitats as any kind of species in the game!