Well i thought id just add the final model , although basic to look at, i'm pleased with the dynamic aspect of it.
I can change the overall dims and the key design aspects using the components options box, and I have assigned the components to different layers for selective viewing of different parts.
Just one last thing! how to miter the ends of the plinth rails in such a way is will redraw correctly?
The answer is probably the scale function but i haven't yet got a full grip on this control in the attributes fields.
Please excuse the pace of learning...
Dan