Making a 1:12 scale stone wall using builders foam

Start with a sheet of rigid insulating builders foam and cut to size. I cut mine with a band saw or a scroll saw, which left a nice smooth edge.
When drawing on your stones, it’s best to get started by looking at some pictures of stone walls. It’s all too easy to make your stones get too big or too small. 

I found it easiest to start by drawing them with a pencil, applying enough pressure to indent my lines. 

Next I filled a medium sized ziploc bag with pebbles of assorted shapes and sizes. I think mine were originally purchased for an aquarium or something. I placed my bag on a section of incised wall, then I used a wooden dowel as a rolling pin to press the stones into the foam board. Sometimes I used the side of a hammer when I got tired of rolling, whacking without too much force, otherwise I’d have torn the surface of the foam. The pebbles do tend to wear through the bag, needing to be rebagged now and then. I tried pressing them into the foam board without the use of a bag, but it got pretty messy. The smaller stones tend to break down and you wind up with lots of stone dust.

The next step was to go back over my lines to define the shapes of the stones. Sometimes I used a metal skewer, holding it like a pencil, tracing my initial lines to deepen and define them. Sometimes I found a small screwdriver gave me a look I wanted, other times I used a small wedged tool. It gave some of the stones a slightly different edge. I think it was part of some arts and crafts kit we bought for one of the kids. 

I knew I needed more texture, so I got out 3 different sized chains. I’d drop a piece of chain down in a sort of clump, then roll over it with my dowel. You don’t want to press too hard or you’ll break through the foam surface and you’ll wind up with a messy area. I did this with each size of chain. I probably didn’t need to use the finer sized golden one, but what the heck, why not?

The final textures were applied to stones individually. For some I applied a little joint compound, using the tip of a palette knife, then patted gently with the tip of my finger. For others I dabbed a little glue on the stone then used the palette knife to apply a little artists’ texture paste. I found the texture paste easier to use than the joint compound. It’s “fluffier” than the wetter joint compound, but they gave me slightly different results.

On other stones I applied a little paperclay, first applying a little glue to the stone. I’d take a small ball of paperclay, press it out between my fingers and press it onto the stone, smoothing down the edges with the tip of my palette knife or the tip of the eraser on my pencil.
By the way, on the paperclay, joint compound, and texture pasted stones, once dry, I sanded their surfaces gently with an emery board.

On still other stones I used the rough paper of an egg carton. I’d cut off a small piece, then gently pry the section apart and peel off a piece, applying it with a bit of glue.

After I’d finished applying texture I’d go back and deepen or define the edges of the stones wherever I felt they needed it.

The stone wall is then ready to be painted.


  1. Thanks for the information Grazina.

  2. The variety of methods you've incorporated have resulted in some very convincing stone textures. I particularly like the idea of rolling over real stones to indent the surface of the foam- Very Clever!!! :D