I looked at a lot of examples of mountains built with foam, and most of them were stacked sheets of extruded polystyrene (XPS) normally used as insulation and normally about 2 inches thick. Those examples were not very big mountains. Not only was that going to be expensive, but it was going to be a lot of work stacking that many sheets. I also looked at a variety of other ways to build mountains with other materials, and didn't like where I was ending up. Along the way, I came across this stuff called "geofoam" - very large blocks of styrofoam that they build roads out of. I had never heard of building roads with styrofoam before, so had no clue where they did such silly things. Certainly not in Minnesota. But my search took me to a local construction supply company, who was a distributor for a local geofoam manufacturer. And yes, they would sell it to me even if I only needed a small truckload. The sales rep who sold it to me said "you'd be surprised how much foam is in the roads around the Mall of America". He would know, he sold it to the construction company that built the roads.

Once I figured out that the geofoam approach was viable, I got serious about drawing up the design based on 3'x4'x8' blocks of foam. I ordered the foam in early spring (snow was barely gone) just to be sure that, yes, I could really actually buy a truckload of really big chunks of styrofoam. I had it delivered to our company warehouse for storage until I was ready to use it.

Just a side note here: Styrofoam is actually a trademark name for expanded polystyene, simply abbreviated EPS for generic reference to this type of foam. We technically did not use "Styrofoam", we used EPS from another manufacturer who does not own the Styrofoam trademark. But I keep calling it styrofoam anyway because everybody thinks of EPS as styrofoam just like everybody calls facial tissue "Kleenex" even when it isn't that brand.

My trailer is bigger than the average home style utility trailer, but even so, could only move 3 blocks at a time from the warehouse to the layout.

My former neighbor and good friend Greg helped me with the big cuts using the "bow cutter", a style of hot wire cutter. Neither of us had cut foam like this before, so we wondered how well it would work. We were both amazed at how easy it was and how cleanly it cut. Once we were done with the big cuts, it looked like we had simply ordered a few smaller blocks from the supply company in the first place. That's how clean the cuts were. And no little white balls flying in the wind. The mess resulting from cutting styrofoam is why a lot of modelers avoid using EPS, and stick to sheets of XPS if they use foam at all. But there is no mess in hot wire cutting.

I had drawings showing where full (uncut) blocks would be placed and what sizes of smaller blocks we needed to cut. You can find those drawings on the layout design page. Ending up with the right combination of smaller blocks required actually mapping out the cuts for each big block. Using those block cut maps as our guide, we drew lines all the way along each side of the big block to be cut, and very carefully followed the lines with the hot cutting wire.

After all the big cutting was done, we placed the various blocks according to the block map. Then we stood back and admired the fact that the collection of blocks actually somewhat resembled the drawing.

The next step was to make some smaller angle cuts, and then begin "gluing" the blocks together. For the "glue", I used the expanding spray foam usually used to seal around window frames, etc. It is very sticky and holds well. Later in the process, I would drop hot rebar through the middle of the blocks, and then use a sledge hammer to drive the rebar into the ground, to anchor the blocks. I sprayed foam around the rebar to glue that to the blocks as well. Between the blocks being all glued to each other, the rebar, and 3000 lbs. of dirt on top of each big collective chunk, I don't think they're going to blow away. Or if they do, finding my foam back will be the least of my concerns at that point.

This is what the Hot Wire Foam Factory calls their professional hot wire tool kit. They are good tools and work well, but for small projects. I found that my needs were one step above professional. I needed the industrial tools. I guess professionals make smaller sculptures. When you get to stuff my size, they call you industrial. Or crazy.

I put a lot of work into getting those big chunks of foam in place. If I was going to screw up because I hadn't figured out what I was doing yet, I wanted to screw up a smaller piece. So I took a few of the smaller pieces that were left over from carving the big blocks to size and started practicing. My first couple of samples were not so good, but I quickly got a feel for the tools. I had a tendancy to over-think what I was going to do. I had to teach myself to stop thinking and just start cutting. The less I thought about it, the better it turned out.

This was one of a handful of pratice pieces that I carved in the basement workshop, then took out to the layout for a "fit check". Just set it there and stand back and contemplate whether it looks like rock.

When it came to carving the mountain "texture", this tool was the most useful. The wire options included blade material which you see pictured here. It isn't sharp like a knife, just wider than wire and flat. It helps guide the cutting process. You can bend this stuff up any way you like, so some of the effects were created by bending the hot wire differently.

Early on, I had planned to put a tunnel in one of the big mountains. I decided against that for technical and logicstical reasons, and would create something else just for the sake of having a tunnel. That idea morphed a few times before realizing I had enough big scraps of foam left, I could build an entire small third mountain just to have a tunnel.

You get a lot of small scraps in carving the texture into the mountains. I was against putting any scrap foam into the landfill. Larger pieces were saved for future use in carving other stuff. I save all the small scraps like you see here and later melt them. You do not want to burn polystyrene, but when exposed to heat (like a plumbers torch) it melts to almost nothing. Styrofoam is about 98% air, so many garbage bags of scraps like pictured here reduce to half a grocery bag of crunchy stuff. And one refill of propane for the plumbers torch is enough heat for those many garbage bags to more or less go away. I saved some of the more interesting random designs that appeared in the melting pot for use in art projects. The rest will become small artificial landscape features (mostly rock with character) in the layout.

Just in case you're wondering about recycling, unfortunately EPS foam is the one type of plastic absolutely nobody accepts for recycling. I suspect it just isn't sufficiently cost effective to recycle mostly air. And it isn't biodegradable, so don't use it unless you're building a mountain!

Movie makers always like to point out "no animals were hurt in the making of this movie". I would like to point out that "no landfills were hurt in the making of this railroad layout".

The detail carving is now done. The cracks between blocks have been covered over with polymer modified morter. You can't even see where the boundaries between individual blocks are anymore. The mountains are ready for coating. This view is looking west, south mountain on the left, north mountain on the right.

This is the view from the south looking north.

This is the view of the other side of the south mountain looking at it from the north.