Hi again.
Perhaps I am guilty of making this sound too complicated (easy for a newb perhaps)...
Below are the (I guess you could call them 2D shapes?) lines that I want to start with (the rest of the circuit will be drawn in AC3D).
The black area denotes the required resultant shape, whilst the green area shows the bits that I need to cut away to achieve the shape.
If I was in Corel/Illustartor etc I would simply select the 2 non-required bits and cut them away from the main exterior shape thus leaving holes where they used to be.
From that point I can add a texture, extrude it by a couple of mm and then start to add the scenery - the sticking point is simply getting the shape in the first place to be (in effect I think) a flat surface.
Please excuse the crap understanding of 3D terminology but coming from a 2d design background its a bit of a learngin curve .
I hope this makes more sense - essentially I just want to make a solid from this with the green bits taken away and holes left in their places - this would make my race circuit as in the upper pic.
Many many thanks
Owen