How to Carve a Foam Base

I have been wanting to carve a foam base for one of my models for a long time, but I have been very intimidated. I bought an electric foam carving kit over a year ago and hadn’t even opened the package. Recently one of my subscribers sent me a picture of a base she had carved and when I asked her what she used to carve it she explained that she uses only a pencil and craft knife to carve her bases. Well, I can do that!

I decided to carve a base for my new Village Church as I want to submit it to Lucy Foxworth’s Easter/ Spring contest. Lucy holds a contest 3 times a year, so if you miss this one, consider entering her Halloween contest or her Christmas/ Winter contest. I decided that I wanted to carve a stone wall, steps, and add a walkway. I made this base a little larger than I would normally would so I could use it in future photo shoots of other models.

There are several YouTube videos I have found with examples of people carving foam bases, usually for D & D or other roll playing games. RPArchive has a lot of terrain videos. I have only begun to scratch the surface of his videos. I also found this video about carving stairs from StorycraftSociety

How To Carve a Foam Base

Size of my finished base is approximately 14″ W x 15 1/2″ D X 1″ H.

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Foam Base Specific Materials

  • XPS pink Insulation Foam. The pink foam goes under the name Foamular and is made by Owens Corning. It comes in 1/2″, 1″ and 2″ thickness. While I give you a link to it on Amazon, it is much cheaper to buy a big piece of it at a hardware store like Lowe’s or Home Depot. My husband had some 1″ left over from a project so that is what I used. Unlike the foam that you find as packing material, XPS foam is manufactured in a continuous extrusion process that produces a closed cell form of foam insulation. Packing or EPS foam is manufactured by expanding spherical beads in a mold and then using heat and pressure to fuse the beads together. Hence XPS is a much tighter foam and easy to carve. You can also buy white 1/2″ XPS foam from Amazon, as well as white 3/4″ XPS foam. These both seem to be marketed towards gamers.
  • A yellow pencil. You will remove the eraser. I am so used to using mechanical pencils I had to dig through drawers to find one!
  • Craft Blade like an X-Acto knife or Cricut TrueControl Knife. I also have a hand-held knife called the Excel Knife. It is nice in that it uses the cheaper craft blades, but the blade doesn’t work its way loose like the blade in my X-Acto knife often does.
  • Olfa Utility Knife or small saw like X-Acto Saw. This is to cut your base size from your larger piece. I used my X-Acto saw because I had it handy and my husband misplaced my Utility Knife, but the cuts it leaves are not smooth. This was fine in this instance as I wanted the look of rough hewn stone. If you want long smooth cuts, buy the Olfa Utility Knife.
  • A Metal Edged Ruler 
  • Glue: Clear Gorilla Glue
  • Old toothbrush
  • Matte Mod Podge mixed with acrylic paint as primer, and acrylic paints in greys and browns to color stone.
  • Optional: A cordless, rechargeable, handheld rotary tool. I carved most of my base by hand, but remembered I had this and used a small drill bit at the lowest setting for one side of the base to see how it would work. I still drew out my stonework by pencil, and also still needed to use my craft blade to round out some of the stones, but it did speed up carving my base. I also actually broke open the heat carving kit I bought a year ago, but didn’t like the results with this project as it melted the foam too smooth to look like rocks.

Steps to Carve the Foam Base

Cut Your Board to Base Size

I cut my base a bit large as I decided I would use this base again in photo shoots. Here is a YouTube Video on how to get smooth cuts using your Olfa Utility Knife. He uses the knife beginning at 4:44. I actually liked the rougher cuts I got with my X-Acto saw as I wanted the stone to look rough hewn.

Plan and Draw Out Your Base With A Pencil

Don’t worry about making pencil marks all over your base. You will use a combination of Mod Podge and acrylic paint to seal and color your foam.

At this point I also planned out where my steps would be in my wall and cut out the stair block.

Slice your stairs, then glue them back together.

I used this YouTube Video for carving stairs. He shows his trick for making stairs at 4:59. Though he used a heat saw, you can obtain the same results with your Olfa Utility Knife or X-Acto Saw. In the video he uses a hot glue gun to glue his stairs, but I thought the hot glue would be too bulky for my little stairs so used Gorilla Glue.

After gluing your steps together, use your pencil and craft knife to cut stones into the steps. You can texture the foam by hitting it with a crumpled up piece of aluminum foil or a small pumice stone. Put your steps aside. You will not glue them back into the base until after you paint it.

Draw & Cut Out Your Rock Wall

I used my pencil to draw all of my side walls first. I went over the lines again with my pencil to make them deeper, then used the smashed up eraser side of my pencil and my craft blade to further carve out the stones.

On the bottom side of the board, cut little Vs into the board between the rocks. This will help to create the undercut look of the rocks on the bottom. When you are done with the sides and bottom, you will need to draw out the top of the rock wall. This is done in the same way as the sides. Any place where your foam is too smooth, you can hit it with your crumpled aluminum foil ball or pumice stone to give it a stone looking texture.

Remember to carve the side walls of your stairs, and any path you want at the top of the stairs. Check the fit of the stairs into the base, but don’t glue them in.

You can leave the top of the base level with the top of the rock wall, or carve it down a little if you want the top of the rock wall to be slightly above ground level. I originally tried to do this with my heat kit, but didn’t like the results as they were too irregular. I ended up using my X-Acto saw to scrape out a little depth. I would have used my OLFA Utility Knife, but after a prolonged search my husband has admitted he has lost it. I have ordered another one and we have had a discussion about returning tools to their proper place immediately (even better would be if he would stop borrowing my tools!) As soon as my new knife arrives, I will invariably find my old one.

Clean off any loose bits of foam using an old toothbrush.

Paint Your Base

Use a 50/50 mix of Matte Mod Podge and acrylic paint to seal your foam base. The Mod Podge will also strengthen it. Use the color that you want as the mortar in your stone wall. You can use a different color to seal the ground area of your base if you want to. I would have used white for this part if I was going to add snow, but thought the dark grey would work fine under grass. You can use 2 coats if you think you need them.

Paint the stones of your wall. Use many different colors if you want your stone wall to look realistic. Once finished, mix a little bit of black acrylic paint with several tablespoons of water and apply a black wash over all of the stones. Let dry.

Glue the stairs into the base. Now you can either add grass for a spring or summer look, or snow for winter.

I used JTT Scenery Products Blended Tuft that I bought at Hobby Lobby to add the grass. You add it using Mod Podge, but it is a bit of a pain to get even coverage. They also have green grass mats that can be cut to fit.

I was rather amazed at how easy this was, and now feel silly that I have always been too intimidated to carve a foam base before. I foresee a lot of foam bases in the future!

I would love to see any foam bases that you carve. Please share a photo of them with me by emailing me at Jackie@acottageintheforest.com

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