Turning a 100 × 60 × 40mm XPS Foam Sheet into an HO Scale Model Railway

Name: DIY Castle Wall Terrain Kit – XPS Foam Tabletop Scenery Set
Brand: Hobby Foam Supplies
SKU: CAS_WALL_KIT
Price: 45.95 AUD
Availability: InStock

August 31, 2026

One Sheet. So Many Possibilities: Turning a 100 × 60 × 40mm XPS Foam Sheet into an HO Scale Model Railway

When you think about a model railway base, you might immediately think of plywood, MDF or another rigid board.

But what if the base could do much more than simply support your railway?

What if the same piece of material could become the base, the hills, the riverbed, the embankments, the landscape and the foundation for your scenery — before finally disappearing under paint, grass and texture?

That is exactly what makes a 100 × 60 × 40mm XPS foam sheet such an interesting material for model railway building.

At Hobby Foam Supplies, our Australian-made high-density XPS foam is designed for hobbyists, model makers, terrain builders and model railway enthusiasts. The range includes 40mm-thick sheets, and our project gallery already features customers using 100 × 60 × 40mm XPS for scale-model terrain and HO-scale railway scenery. (Hobby Foam Supplies)

The idea behind this project is simple:

Don't think of XPS foam as just a base. Think of it as the beginning of the entire landscape.

🚂 From a Sheet to a Complete HO Scale Railway

Imagine placing one 100 × 60 × 40mm XPS foam sheet on your workbench.

At this point, it doesn't look like much.

It's simply a flat sheet of foam.

But that 40mm thickness gives you something very valuable:

Depth.

And depth means you can cut into it, carve it, shape it and build into it.

Instead of attaching a separate scenery material to the top of a base, you can use the foam itself to create the terrain.

Your project can progress through a simple transformation:

XPS foam → strong base → carved terrain → railway and scenery → painted landscape → finished HO scale railway

And the remarkable part?

The original sheet is still doing the job.

1. Start With One Strong Base

The first job of the XPS sheet is the most obvious one:

It becomes your base.

The 100 × 60cm footprint gives you a substantial area for an HO scale scene, while the 40mm thickness provides depth for terrain modelling.

You don't necessarily need to start by adding another separate sheet underneath simply to create your scenery foundation.

The XPS itself can be the starting platform for your project.

This is one of the key advantages of using a thicker sheet rather than a very thin foam sheet.

You have enough material to work down into the base, rather than having to build all of your scenery above it.

Hobby Foam Supplies' project gallery shows a customer using a 100 × 60 × 40cm XPS foam base for scale-model terrain, as well as another project using 100 × 60 × 4cm and 100 × 60 × 2.5cm XPS for HO-scale model railway scenery. (Hobby Foam Supplies)

Why is this useful?

Because your base is already:

lightweight
substantial
easy to cut
easy to shape
suitable for carving
suitable for adding scenery
ready to paint and texture

And most importantly, it gives you 40mm of depth to play with.

2. Don't Leave the Base Flat — Carve Your Landscape Into It

This is where the fun really begins.

Your first instinct might be to put your railway track directly onto the flat foam.

But before doing that, look at the foam differently.

The flat surface is your starting landscape.

Take a pencil and sketch your proposed scenery.

Perhaps you want:

a river running through the layout
a hill in one corner
a mound beside the railway
a valley
a road cutting through the landscape
a raised railway embankment
a small cliff
a tunnel entrance

You can mark all of these directly onto the foam.

Then start shaping.

XPS foam is particularly useful for this because it can be worked with hobby knives, hot-wire tools and other suitable modelling tools to create terrain and detailed topography. Hobby Foam Supplies' model railway guide specifically highlights XPS for carving embankments, riverbeds, elevations and other terrain features. (Hobby Foam Supplies)

3. Carve a Riverbed Into the Same Base

Let's start with one of the simplest transformations.

A river.

Draw a winding line across the foam.

Now carve down into the surface.

You don't have to cut all the way through.

Instead, create a shallow depression.

Then gradually deepen sections of the river.

You can create:

gentle riverbanks
deeper channels
bends
waterfalls
rocky sections
bridges
small ponds
streams joining the main river

The surrounding XPS remains intact.

So you now have:

Base + riverbed + riverbanks

all from the same sheet.

This is much more interesting than simply painting a blue river on top of a completely flat board.

The river actually has physical depth.

4. Create Hills and Mounds From Your Base

The same principle works for hills.

Instead of adding a completely separate material to create a hill, you can work with the 40mm thickness you already have.

Leave some areas high.

Remove material around them.

Then gradually shape the transitions.

You can create:

Gentle rolling hills

Use broad, smooth transitions.

Small mounds

Create isolated raised areas.

Railway embankments

Leave a raised strip underneath or alongside the track.

Rocky slopes

Cut more aggressively and add texture.

Cliffs

Create sharper changes in elevation.

Valleys

Lower the area between two raised sections.

Suddenly, your flat 100 × 60cm sheet has become a three-dimensional landscape.

5. Your XPS Base Can Become Your Railway Embankment

Model railways look much more realistic when the track isn't simply sitting on a completely flat surface.

Real railways travel through landscapes.

They cross:

valleys
embankments
bridges
cuttings
hills
tunnels
rivers

Your XPS gives you the opportunity to reproduce these features.

For example, you can carve away the surrounding terrain while leaving a raised section for the railway.

Now the track has a natural-looking embankment.

Or carve down on both sides of the track.

Now you have a railway cutting.

Or lower the landscape and create a bridge crossing.

The foam becomes the terrain surrounding the railway rather than merely something hidden underneath it.

6. Pin Your Trees and Figurines Directly Into the Foam

Now comes another useful feature of XPS foam.

Once your landscape has been shaped, you can begin adding the little details that make an HO scale scene feel alive.

Think about:

🌲 Trees
🚶 Figurines
🚧 Signs
🌳 Bushes
🏠 Small scenery items
🚦 Trackside details
🪧 Posts and markers

For suitable lightweight items, you can use pins, skewers or similar supports directly into the XPS.

That means you don't necessarily need to find a hard surface underneath every single tree.

You can position a tree directly into your landscape.

Push it into the foam.

And there it stays.

The same applies to suitable miniature figures and other lightweight scenery components.

Hobby Foam Supplies' geography project guide demonstrates adding miniature trees, animals and other decorative details to XPS landscapes, while the model railway guidance discusses using suitable pins and adhesives with foam. (Hobby Foam Supplies)

A small tip

For heavier objects, don't rely solely on the foam.

Use an appropriate support, pin, adhesive or mounting method according to the weight of the item.

7. Glue Your Train Track Directly Onto the Foam

Now it's time to bring the railway itself into the landscape.

Once your terrain is shaped, you can position your HO scale track.

For appropriate track and scenery applications, suitable foam-compatible adhesives can be used to secure components to the XPS.

This means your foam is now doing another job:

It is supporting the railway.

You can create the track route around your landscape rather than designing the landscape around a completely flat base.

For example:

River → bridge → rising track → hill → tunnel → descending track → station

All of those elements can be incorporated into one continuous piece of XPS terrain.

Hobby Foam Supplies specifically positions its high-density XPS for model railways and notes that it can be shaped for embankments and railway scenery. (Hobby Foam Supplies)

8. Build the Landscape Around the Track

Once your track is positioned, start thinking about everything around it.

A railway doesn't exist in isolation.

You might want:

grass
trees
rocks
roads
houses
stations
fences
bridges
tunnels
farms
hills
rivers
footpaths

And because the XPS is already your foundation, these features can be integrated into the same landscape.

A road can cross the railway.

A bridge can cross the river.

A hill can rise behind the station.

Trees can be pinned into the foam.

Buildings can be glued to prepared flat areas.

Rocks can be positioned around the river.

The scene becomes much more believable because everything is connected.

9. Then Comes the Magic — Paint the Foam

At the beginning, you had:

Black XPS foam.

After carving, you might have:

a river
hills
railway cuttings
embankments
roads
valleys

But it still looks like foam.

Then you paint it.

This is when the entire project starts to transform.

Acrylic paints can be used to develop the basic colours of the landscape, followed by washes, dry brushing and scenic textures to build depth and realism. Hobby Foam Supplies' own XPS projects use painting and texturing to transform raw foam into finished scenery. (Hobby Foam Supplies)

10. Start With a Base Colour

Don't worry about making it perfect immediately.

Start broad.

For a countryside railway, you might use:

Brown for exposed earth.

Dark grey for rocks.

Green for grass.

Blue for water.

Grey/brown for roads and paths.

The first coat establishes the overall landscape.

Then you can start adding detail.

11. Add Darker Colours Into the Recesses

Here's where carved XPS really starts to work for you.

Your riverbed has recesses.

Your rocks have cracks.

Your hills have texture.

Your railway cutting has shadows.

Your road has edges.

A darker wash can settle into those areas and create depth.

Instead of a completely flat painted surface, you now have natural variations in tone.

12. Dry Brush the Raised Areas

Once the darker colours are dry, lighter paint can be lightly brushed across raised surfaces.

This catches the texture.

The result can make:

rocks look more three-dimensional
cliffs look deeper
paths stand out
terrain contours become visible
carved details become more pronounced

This is a particularly effective technique on textured XPS.

13. Add Grass, Ballast, Rocks and Other Scenery

Now the foam is almost completely transformed.

Add:

static grass
scenic grass
ballast around the track
gravel
sand
miniature rocks
bushes
trees
fencing
buildings
figures

The railway begins to disappear into its environment.

And that original XPS sheet?

It is still underneath everything.

It has simply become the landscape.

14. From One Sheet to a Complete HO Scale Scene

Let's look back at everything that one piece of 100 × 60 × 40mm XPS foam has done.

At the beginning:

One flat sheet.

Then:

A strong project base.

Then:

A carved riverbed.

Then:

Hills and mounds.

Then:

Railway embankments and cuttings.

Then:

A foundation for trees and figures.

Then:

A surface for track and scenery.

Finally:

A complete painted HO scale landscape.

That's a lot of jobs for one piece of foam.

But It Doesn't Have to Be a Train Layout

This is perhaps the most important point.

Although this particular example shows an HO scale railway, the same 100 × 60 × 40mm XPS sheet can be used for many other projects.

Dioramas

Create a complete miniature environment from the base upwards.

Wargaming

Carve hills, trenches, roads, cliffs and battlefield terrain.

Hobby Foam Supplies' project gallery includes XPS bases being used for wargaming terrain. (Hobby Foam Supplies)

School Projects

Build geography landforms, volcanoes, mountains, rivers and landscapes.

Architectural Models

Create stepped landscapes, foundations and terrain around buildings.

Miniature Displays

Build a permanent display scene for models and collectibles.

Craft Projects

Cut, shape, paint and build almost any lightweight three-dimensional scene.

The versatility of XPS is one of the reasons Hobby Foam Supplies markets the material across model railways, wargaming, dioramas, school projects and other modelling applications. (Hobby Foam Supplies)

Why 40mm Thickness Makes a Difference

A 40mm sheet gives you something a thinner sheet can't provide as easily:

Usable depth.

That depth allows you to make the material work in multiple directions.

You can build up.

You can carve down.

You can shape across.

You can attach into it.

And you can finish over it.

That's why the 40mm thickness is particularly interesting for terrain projects.

You're not simply putting scenery on top of the foam.

You're using the foam to create the scenery itself.

A Simple Project Plan

If you're planning your own HO scale scene, try this approach:

STEP 1 — Plan

Sketch your railway, river, hills and major structures.

STEP 2 — Start With the XPS

Use your 100 × 60 × 40mm sheet as the main foundation.

STEP 3 — Mark the Terrain

Draw your river, hills, roads and railway route.

STEP 4 — Carve

Create the major elevation changes first.

STEP 5 — Position the Track

Test your railway before permanently securing everything.

STEP 6 — Add Scenery

Pin suitable lightweight items such as trees and figurines into the foam.

STEP 7 — Glue

Secure track and compatible scenery using appropriate foam-safe adhesives.

STEP 8 — Paint

Base coat the terrain, then add washes, highlights and texture.

STEP 9 — Finish

Add grass, ballast, rocks, buildings, figures and other details.

STEP 10 — Enjoy Your Railway

Step back and look at what started as a single foam sheet.

One Sheet. Multiple Jobs. One Finished Landscape.

The biggest advantage of using XPS foam this way isn't simply that it's easy to cut.

It's that the same piece of material can perform several different jobs throughout your project.

Your 100 × 60 × 40mm XPS sheet can be:

Your base.

Your terrain.

Your riverbed.

Your hills.

Your railway embankment.

Your scenery foundation.

Your support for trees and figurines.

Your track foundation.

And finally, your finished landscape.

What begins as a simple XPS foam sheet can end as a detailed HO scale railway scene.

And that's the beauty of XPS foam:

You don't just build on it. You build with it.

🚂 Ready to Start Your Own HO Scale Railway?

Explore the 100 × 60cm XPS foam range from Hobby Foam Supplies, including the 40mm thickness, and start turning a simple sheet of XPS into your next miniature world. The foam is Made in Australia and is available in thicknesses including 40mm, alongside other options for different modelling requirements. (Hobby Foam Supplies)

Shop XPS Foam for Model Railways & Terrain