How to model a cliff or rock face


Observation is everything when it comes to creating a low-cost detailed rock face.

Rock faces and cliffs are distinguishing features of many locations. They’re prevalent in nature, and are a common feature resulting from the construction of railway lines where rock is exposed when making cuttings and building tunnels. It should be part of your study of the topography of an area you're modelling.

The rock face we’ve modelled here is generic and demonstrates the techniques I use, but you should research the type of rock you want to model and take reference photographs of the colouration and structure for later use. It’s not particularly difficult to make and you can create dramatic scenery if you want.

Make it look like the railway is passing through your terrain – it’s too easy to make it look like a flat railway with piles of rock either side. Many North American layouts feature dramatic mountainous scenery and are worth investigating.

Shopping List

Extruded insulation foam

Poly Fibre

Acrylic paints

Wall filler

Ground foam

Wood saw

Rasp

Files

Scribe

Wire brush

Drill and drill bits

1" paint brush

Spatula

Mixing bowl

1

Peel and discard the aluminium foil covering the foam insulation sheets, then cut it to shape with a wood saw.
How to model a rock face

2

Study photographs of real locations you want to base your model on, then distress the foam with rasps, files, wire brushes or drills to get different shapes.
How to model a rock face

3

Mix wall filler to the consistency of double cream using a spatula. When mixing, add water a little at a time and mix before adding more.
How to model a rock face

4

Brush the filler onto the foam. It’s better to add several thin layers to aid drying and is a necessity if you’re building to a depth greater than 10mm. This is a good time to blend joints between pieces of foam.
How to model a rock face

5

Just like when baking, you’ll find the mixture produces peaks, so once dry, sand them down. Add final detailing here - fine strata can be produced using a wire brush and scribers.
How to model a rock face

6

Tilt the work at about a 45-degree angle. Start by adding an overall base colour wash over the cliff/rock face. I used acrylics and emulsion paints.
How to model a rock face

7

While still wet, add light brown, dark brown, green and grey washes. Use plenty of water – you can always add more layers of wash, but you can’t take it off as easily. Start at the top and let the colour work its way down. I retain the base colour in the palette and add other colours to blend better.
How to model a rock face

8

Dark-coloured pastels can be worked into the crevices to emphasise these more. You need to be subtle because it’s easy to overdo. Ensure the base coat is dry first.
How to model a rock face

9

Choose a light colour for the highlights and drybrush this onto the rocks. Add paint to the brush, clean it on a rag, then drag the brush lightly over the surface so that only the raised surfaces receive paint.
How to model a rock face

10

To simulate lichen and moss, take some off white and yellow-brown paint and flick it at the surface using an old toothbrush. Don’t overdo this effect.
How to model a rock face

11

Tease out pieces of PolyFibre and lay out on newspaper, then coat with hairspray.
How to model a rock face

12

Transfer the piece to another sheet of newspaper and sprinkle on ground foam – I used Hornby R8874. Place in a safe location to dry.
How to model a rock face

13

Stick the vegetation so that it hangs down the face in a random fashion. I used superglue and an activator for quick results. Glue one or two spots at one end, then stretch the PolyFibre until you have thin coverage, then glue that side down.
How to model a rock face

Top Tips

  • This job is messy, especially if you’re cutting lots of foam. You may want to use a dedicated space that's easy to clean afterwards. A vacuum cleaner is essential for cleaning up.
  • Insulation board is obtainable from your local wood yard or builder’s merchant. Ask your supplier to cut it into smaller, more manageable pieces.
  • Join foam sections together with a hot glue gun or specialised foam glue.
  • Wear a dust mask when working with any material that produces dust.
  • The finer the detail you add to a rock surface, and the lighter the colours you paint it, the more distant it’ll look in a scene. Add less surface detail to rock faces close to the viewer.
  • When applying the powder filler, you may find it easier if you cut down the bristles of your brush.

So there you have it, our guide on how to model a cliff or rock face for your model railway. 

If you're interested in placing trees on your layout, our online guide will help you get to grips with ‘planting’ trees on your model railway. 

Looking to create bushes next? Watch one of the Woodland Scenics experts show you how. 

Need more advice? Take a look at the BRM Techniques page for all our latest guides and advice articles.