I'm working in "N" and "Z" Scale.  I had 2 4' x 8' tables put together in an L shape in "N" scale that could run four trains at the same time with out any wrecks,   Steam Engines are my favorit. That table I had when I lived in Jacksonville, Florida.   Now I'm living in Georgetown, Ohio.  I built A "Z" scale layout it's 73" x 32".  I also like working on Trestle bridges.  I've been looking for information But I guess I'll have to break down and buy a book!  I have been working with a program called 3D Max8 to design some bridges.