if you want a REALLY big cube, they MIGHT have a scaling function

basically, you grab a borg cube...put it there
then under 'edit' tab (if they have it) go to scale...should say 1.0.....change it to 4.0

ta-da one big honking cube

borg generic base...build it out of cubes and spheres...make them inert
slap some defensive guns on it

There are limits to the game engine and the tool
but there is no limit on your imagination

also, very often in tools like this, if you make the cube...or anything else inert...or
non-functional, you might be allowed to overlap models, so you could make...say a long
cube by meshing 2 cube 'keep in mind, would just be for show, then at one end bury
a borg sphere with just a bit showing at the top

stick it on a big rock.....borg listening post.