This is a small section of a 600ft X 800ft battle map of a sewer I made using techniques I pieced together with the FM8 help files and some awesome tips from MarkOliva (thanks Mark!). The technique most useful was Actions -> combine polygons -> subtract (to create cutouts that I could bevel and drop shadows). I did this twice. Once for the sewage in the brick floor and once more to make the sewer walls appear raised.
Another thing I learned was that you need to turn Map -> display quality-> special effects - high res or all the bevels look pixilated and ugly. you can work at low res and save at low res but when you want to print or display at high quality, you need to set it back to high res.