code: function size(o) {
    var bbox = o.getBounds ? o.getBounds() : o;
  
    var foo = bbox[1].minus(bbox[0]);
    return foo;
  }
docs: Returns a `Vector3D` with the size of the object.
  @param  {CSG} o A `CSG` like object or an array of `CSG.Vector3D` objects (the result of getBounds()).
  @return {CSG.Vector3D}   Vector3d with the size of the object