Mountains
Hi Dewey, Building a mountain is sorta like eating porkchops and turnip greens
You don't think about it you just do it
But I know what you are asking
There are a lot of methods, plaster, foam, chicken wire, paper bags ( thats what I use) and etc.
My favorite book on scenery is kind of an "oddball" its called....
Scenery For Model Railroads, Dioramas & Miniatures by Robert Schlecher. It was published by Chilton Book Co. Radnor, PA. The ISBN # is 0-8019-8503-x. I have never seen this book in a hobby shop and in fact I got mine at Walden Books a long time ago. This book is a step-by-step how-to-do-it publication. Its got stuff in it that I have never seen in the Kalmbach books. What I really like about it is that the author doesn't "toot his own horn" saying "look what I did" ...its just simple, consise, illustrated instructions. Bet you can still find it from on-line booksellers.