2 words; copy, paste..or even better, 1 word; duplicate (probably could replicate, though I've not used that..;)
to be honest, wouldn't it be easier to just create the basic shapes, and then texture with a 'cube-y' texture? unless you like making cubes..just trying to save you some work there..good idea tho..;)

I wish I'd said that.. The Staircase Wit

anahl nathrak uth vas betude doth yel dyenvey..;)