How to Build Model Railroad Mountain Scenery

Modified on March 29th, 2013 at 11:57 pm

This how to build model railroad mountain guide comes from a 4M x 2M HO layout. It is still under construction but the base board, track risers and track laid and ballast are in place.

The materials used to construct the model railroad mountains include broken styrene boxes, expanding foam and plaster cloth.


  1. Carving Knife
  2. Sur-Form


  1. Styrene boxes
  2. Expanding foam aerosol cans
  3. Plaster cloth

First picture is of the various materials used as the actual railroad mountain was being built.

How to Make Model Railroad Mountains 1

Step 1: First make a box section with openings and spray paint inside with flat black water base acrylic. If you look closely at the first picture, you will notice that there is a roof for the mountain to go on top.

Step 2:  Break up the styrene boxes and randomly place them on the tunnel roof.

Tip:  Pick up styrene boxes from a large supermarket

Step 3:  Fill in everything with triple expanding  foam , it will take about 3 cans total. This will taper down into the base board. Break the styrene by hand to give it more random patterns to the edges. Also, by break it down with your hands it can create a cave in the layout above the tunnel opening. Please notice the expanding foam and broken styrene in the picture above as well.

Tip: Aerosol expanding foam can be bought for about $14.00 at Home Depot.

How to Make Model Railroad Mountains 2

How to Make Model Railroad Mountains 3

How to Make Model Railroad Mountains 4

Step 4: Let the expanding foam cure for about 24 hours and then carve the foam using an electric carving knife and a Sur-Form.

Tip: For a more realistic model train mountain, start chopping at the form in any way you please to get random shapes and to ensure there is no set pattern.

How to Make Model Railroad Mountains 5

Step 5:  After finishing shaping, cover it in plaster cloth. Sur-Form will create the mountains and also river waterfalls.

Tip: You want to reconsider using wadded newspaper as some model railroad modelers have had plastic insect problem from newspapers.

How to Make Model Railroad Mountains 6

Step 6: After the plaster cloth hardens for about 24 hours then mix up a soup mixture of plaster and dab it on to reinforce the hard shell.

How to Make Model Railroad Mountains 8

Step 7:  Start priming the scene by using a mixture of grey acrylic primer mixed with water and plaster. (it is a bit difficult to see the waterfall and pond with a river in the photo)

See More Model Train How To Guides with Pictures & Step by Step Directions


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