Foam Board Rock Sculpture

Rock Sculpture - Close Up Detail

Rock Sculpture made from Rigid Foam Insulation board.

I’m trying my hand at sculpting a cool looking rock formation. In my research, I came across several incredible structures that I plan to do after I’m done with this.

For now, I want to share my experience up till this stage. The final result is going to be a lot better than this. hopefully  ;-p

What You Will Need:


  • Cutter
  • Knife
  • Hot Glue Gun + Glue Sticks
  • Wooden Dowels
  • Paints
  • Brushes
  • White Glue / Mod Podge
  • Sand Paper, 120 grit


TOOLS - Brushes and knife



  • Pink Insulation Foam (Rigid Foam Board)
  • White Glue
  • Mod Podge

Rigid Insulation Foam

White glue and mod podge



rocky cliff - giant mountain

Tianzi Mountains China

chines rock mountains

chinese mountains

Rock cliffs in nature

Balance in nature - rock structure

Beautifully detailed rock cliff close up

Neat ancient natural rock towers

Rock Face Cliff

Towering Rock Formation

Research is the key to success. I scoured the internet for days looking for images of rock structures. The ones that caught my eye immediately were the Tyantszu Mountains in China. They look epic. Something right out of Avatar.  However, there aren’t a lot of images that illustrate the intricate cuts and fissures of the rock formations up close.  So i was forced to look elsewhere. Thank God, I did because for one thing I kept learning a lot about geology and the formation of these structures over time. Knowledge aside, It helped me find the right sources for inspiration to keep going forward.

We’ll start with the basic.

I knew I wanted to create miniature towering rock giants so I estimated the height versus width ratio. I started by cutting around 30 squares of 2.5″ x 2.5″ from the foam board.

Circle the center of the square on it’s flat side with hot glue. Take the next square and stack it flat on top of the first square with glue on it. Hold it together for 5 seconds which should be enough. They are super lightweight so they will not slide off unless you really push them. Keep gluing the center of each new square to add another block on top.

I created 3 towers of varying heights. The biggest one holds 12 squares of the insulation foam board. The other holds 9 and the last has 6 squares.

The tallest tower has two larger block at the top that i cut a little bigger than the rest. I did this because (a). It adds dimension, and (b). I wanted to place something on top. I’ll get to that part later as I haven’t completed it yet.

After completing the first stacked tower, Take a wooden dowel and insert it in the middle of the square from the top and push it until it reaches the bottom. It should slide down easily unless you smeared hot glue around the middle of the stacked squares in which case it might resist a little but applying pressure should break the dried glue inside and the wooden dowel will go through it.

Let them sit for 10 mins.

Grab a knife and start cutting off angles.

Cut grooves and crevices.

Dig a bit on some parts.

Use sandpaper, grit 120 or close to it.  You want the kind of grit that smoothes off the angles from the cutting.

Take a break

Come back and see where the the parts could need more definition. Shape as needed.

Use sandpaper again to smooth out the new edges.

Sealing the porous body of the rigid foam board.

I used white glue / elmers glue (The kind you use for craft or kids stuff).

Get ready to get sloppy. Take a brush and dip it in glue and start slopping it on the structure. Make sure to cover each part of it and let it dry for a couple of hours.

Do it once more and let it sit overnight.

It’s time to Paint

Similar to sealing it, i took black acrylic paint and and added white glue into the paste and brushed it on. One coat is enough. Let it dry overnight.

Colour is imperative to making a believable rock. Looking at the reference images, it’s easy to find at least 5 or more different colours. For my rock formation, i used blue, silver, yellow and rustic orange, and white for the highlights.

Taking one colour at a time, and sometimes mixing a couple at the same time, i simply painted it until i was happy with the overall look.

Using a short-bristle brush ( I made one by cutting off 1/2″ off the top of a regular sized brush)

Lightly dab the brush with white paint. Then brush off the excess before you apply to the rock.

Any issues with the paint or error can easy be removed with a sponge or a paper towel.

Rock Sculpture - Full View


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