Terrain Project: Lycanthrope Cave

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I started this project for Gen Con So Cal so one of my DMs (Sheridan) could have an interesting piece of 3D terrain for a Curse of the Moon adventure he was running; the final encounter was a cave at the end of a series of mushroom-filled Underdark tunnels. AS I've been meaning to get into some terrain design anyway, this was an excuse for me to start using my hot wire foam cutter and make some stuff.


I started with a piece of styrofoam about 18" wide and about 26" long, and a piece of corrugated cardboard slightly larger than that. Styrofoam actually is a pretty weak foam for this purpose--there's a sturdier foam used for building insulation but I'm just experimenting at this point and didn't want to mess up on the "good stuff," and for this purpose it'll work just fine. Likewise, cardboard isn't a very good base surface because it can warp from the glue and bend from handling, but I didn't have any hardboard or masonite and (again) I'm just experimenting.

I traced the edges of the foam onto the cardboard so I'd know my maximum dimensions to work with, then used the cardboard as a place to sketch what I wanted to do with the terrain. When I had a general idea of that, I redrew it freehand on the styrofoam using a Sharpie marker, including a naturally-varying outer edge to the foam (ideally, this piece could be used as a cave or as an exterior piece like a ravine, so I wanted the outside edge to be useable. I drew some diagonal lines on the parts of the foam I was cutting away just in case I needed to adjust the foam cutter or cut out small sections at a time for stability and ease of handling (I didn't want to cut out a section of wall thinking I was just cutting what would be open air.

Using my hot wire foam cutter, I trimmed off the outer edge of the foam along my drawn line, giving it a slight bevel so that it would taper inward as you went up just like most natural eroded stone. By cutting away the outside part first, it gave me a little more reach onto the inner cut lines for the next step (most hot wire foam cutters are a U-shape with a wire across the bars of the U, which means that you can't cut any deeper than the length of the U, so cutting away the outer part gave me an extra half-inch or so to work with). In theory you could also use a box cutter or long-bladed X-Acto knife to do this sort of thing, but it'll probably be messier (more tiny pieces of foam scattered about as you work away at it).
Note: Using a hot wire foam cutter on foam produces toxic gases; always do this in a well-ventilated area, preferably outside. It's also probably not a good idea to use your carpeted floor as a workspace, but I had something hard and inflammable to rest the cutter on, and my cutter cools very quickly, so I was taking extra safety precautions.

I then used the cutter to cut out the center part, which really was me cutting away the right-hand (skinny) piece that completely fit within the U-bar of my foam cutter, then cutting away the exposed "eastern" edge of the remaining foam until only the western section remained. Then I trimmed down the cutout parts from the big central cave area to make a couple of smaller elevated areas, just in case I wanted the cave or ravine to have such things. Shown here is the test-fit of the pieces on the cardboard. The cat is Malachi, checking on my progress.

Next step was to glue the pieces in place. People who do a lot of terrain stuff often use Liquid Nails, but I ddin't have any of that so I used what I do have a lot of: Aleen's Tacky Glue. I applied many lines of glue to the underside of the foam and pressed it in place on the cardboard. I knew the second story would be more likely to pop off due to handling, so I straightened two lengths of paper clip for each elevated area and used them as "rebar," inserting one end into the lower foam piece and one end into the upper before gluing it in place. I stacked some heavy books on everything so it would stay flat as it dried, and left it overnight.

When you cut the foam, you end up with a bunch of vertical parallel ridges on the walls that don't look very realistic, so I took some spackle and smeared it along the walls to smooth out those grooves and leave a more natural cave-like appearance. I had also tried to do the same thing on the floor but the spackle I was using was more like a moist foam than the liquid kind and didn't work well for that purpose, so I stopped after trying part of the large room. I let the spackle dry overnight. You could probably just paint on a layer of white glue instead of using spackle.

I have a bunch of dental plaster for the Hirst Arts stuff I do, so I mixed up some thinned dental plaster (still plenty hard enough for terrain use, just not as hard or thick as you'd need it to be to make Hirst Arts bricks out of it) and smeared it over all of the "floor" spaces on the terrain, including the second and third stories. The plaster was just thick enough to retain some texture when I fiddled with it, which kept it from being totally smooth--overall it looks like what a cave created by water erosion looks like. Sometimes the plaster dripped down the side over the spackle, so I used a plastic spoon to smooth it out some. I let the plaster dry overnight. As with the spackle step, you could probably just paint on some white glue (and maybe throw some sand on it for texture). The cat is Parmi, wondering what's up with the gray paste stuff.

Now we're talking! Willow and I had some green paint from painting a windowsill in our apartment, and as Sheridan wanted a greenish look to match a pre-printed flat map card he was using, I used that dark green to cover all of the surface of the terrain, even the outer border of cardboard. While that was drying I took a crumpled paper tower and dabbed some gray paint here and there to give it a bit more color variety (if I had a painting sponge I would have used that, but the rough side of a crumpled paper towel was suitably random). I sprinkled some ballast (small gravel and sand) onto the wet paint in a few areas to give it some texture for the next step. I let this dry overnight.

I used a lighter green (also used on the windowsill) to lightly drybrush all surfaces of the terrain. This made the roughness of the dental plaster, sand, and spackled walls show up better for the purpose of viewing it as a real-world human (rather than a to-scale miniature). In particular I wanted the edges of the first-floor walls to show up better so people at the gaming table could easily see where it ended. After that drybrush I took a different color of green and did some quick drybrushing here and there for even more color variety.

That's basically it. The stuff is slightly shiny, and I think next time I'll spray it will a dull matte spray to take the shine off. Here's a picture of the final terrain with some vampire minis in the big room to show scale. Not bad for about four hours' work.