I googled the size , I assume this is correct :

"The Borg Cube is the most common ship design used by the Collective. They are the mighty gigantic dreadnoughts of the Borg fleet. With a volume of 27 cubic kilometers and spanning more than 3,000 meters on every side, Cubes are the perfect embodiment of Borg mentality and efficiency. "

So if this is 1/1000 scale , it's 3000 meters/ 1000  ,, means you need to build a cube that's 3 meters wide , lulz.

Get building !

Take lots of pix too .