1) I've created a square shape with the line tool.
2) I used Mirror-instance for duplicating this shape and put it
above the original one.
3) I've closed with lines the upper part with the same lower part so now we have
a hollow cube.
Now, the problem i have is attaching all of this into one object and smoothing
all the sides so it would look like a real cube. i've tried to attach the upper and
lower same parts and it can't be done.
Where is the problem ? please help.
(I now there's a cube tool for this to shorten the procedure but i need to know
how to do this in the spline modeling way for something i try to model from a tutorial)