Making stone walls using extruded polystyrene

[Antigona]

Hi!
If you check the newcomers area, you may know I'm still waiting on my Greenleaf Dollhouse. But I'm learning so much thanks to this wonderful forum so I thought I would pay back with a tutorial. I'm not sure if this has been already done as I didn't find it but I guess it won't hurt another tutorial
I'm gonna show you how to make stone walls using extruded polystyrene. Sorry for my english and my meters (lol), but I'll do my best!

In case you don't know (or use other name), this is extruded polystyrene. It's a material used in construction for thermal isolation, and it's pretty cheap (around 3€ per m2)

However I use it for other purposes. On my country is pretty common to build up a Nativitiy scene on Christmas, and I made already three for my workplace. I'm not a religious person but I do enjoy good constructions and specially to build the town part! That's why I feel brave enough to try to show you.
Sadly I don't have any process pictures (as I was not expecting to make a tutorial), but I'll be as clear as possible. This is the final result I want you to achieve:

For more pictures of the final result you can check my Flickr: https://bit.ly/2uz6A6c

Ok, let's start! First, the materials and tools we are gonna need:
-Extruded polystyrene (please note that this is thicker than porexpan or foam)
-Regular cuter (or even a knife). In this case I wouldn't use Xacto Knife as the poly is probably 3-4 cm deep.
-Newspapers or pattern paper (for the initial draw).
-Pencil and pen
-Rules
-Scissors
-Soldering Iron (even the cheapest will do)
-Sand paper (I think same as the sanding paper for wood dollhouses will do! The grain doesn't have to be too big neither too small. If it's too big it will drag away all the material).
-Toothpicks
-Acrylics (at least two colors)
-Brushes

Step 1: sketch the building you are gonna make and draw the plans (blueprint?) on the newspapers. Normally in romanesque architecture buildings tend to be simple, it's not like gothic architecture (specially in rural areas). Please have in mind the measure of "deep" of the poly when planing the plans so everything fits together.

Step 2: when your plans are done, you can transfer them to the poly. I would recommend not to use markers or similar stuff because they may not stick to the shiny surface and you will get all painted (your body and the poly), and then you'll feel ashamed scrubbing yourself with acetone or alcohol. For cuting all the wall parts you have to use a cuter or a knife. Don't worry if you make a notch, there's more work to do.

Step 3: before puting the pieces together, we will prepare the stones (like puting the wallpaper on the dollhouse before assembling, right?). For drawing the stones we are going to use the soldering iron. You can draw the stones with a pencil if you want to, you can design bricks, big rounded stones, unequal stones, something we call "fishbone" (when there are big stones on the corners of the building). Check that the edges between walls are gonna match. Now, pacience. Take the soldering iron (warm) and start drawing the stones. It's ok if it's not perfect, we are gonna work it later. Don't make much pressure or you will basically make a big hole (you could put moss on it, or a little mice if you mess up, so don't worry). If you see that the soldering iron is too hot, I recommend to turn it down and start back later, so we prevent the poly from melting.

Step 4: when all the walls are iron-draw, it's time to take the sand paper. With some care it's time to round all the edges we've made with the soldering; also it's interesting to sand a bit all over it. First, because the paint will have a hard time sticking to the shiny surface, second because it gives some realism to this true old stones. Now it's the time to put some effort on all the things we could've messed before. You can see on my picture I don't do it perfect (plus we collab with some of the users from my work, those lovely elders), but I think it's part of the beauty of the stone to be a bit rough.

Step 5: when everything is already prepared, it's time to paint. Now you have to paint with the DARKEST color, puting special attention to the spaces between stones. I do not use primer before this first layer because the sanded surface absorbs paint perfectly. Once this layer is dry, it's time to apply the real color we want on the building. I apply this paint using a big brush with big hairs and all on a fast way (so I avoid the new color geting inside the spaces of darker colors). Of course you can be all perfectionist if you want!
Once everything is dry I like to mix different colors on fast brush strokes; green, red, yellow... You will be able to make more details and give more realism after it's assembled so it's ok if you want to assemble it first (or add more details then!).

Step 6: time to assemble the creation! In my case, as this scene is only for Christmas, I never glued it. I use toothpicks! Just pinch some of them on the borders of the walls and press them together. I press the houses also on the floor, and that way we can just disassemble it for storage and assemble it back one year later. In case you want to glue it (because maybe you are using is as a basement, or making a little fountain), keep in mind to use a glue that is not agressive with porexpan (a special foam glue).

Step 7: once it's assembled, is time for adding details. If you are planning on make a dollhouse inside, you can work on it. Here's a little bakery and a blacksmith workshop I made;

And we are done! Some considerations to have:
-This bulding is 1:24 kind, and you can see the rock is so rough. I don't think great detail can be achieved with this method (but maybe with another technique, as the poly sands very nice).
-If it's the first time you sculpt something like bricks, I would suggest to draw some patterns first on a paper. It's very important to know what pattern we want on the stones for end up with a realistic result.
-I'm not an expert on lighting dollhouses (in fact we use fairy lights / Christmas for this), but I think it's worth to think it twice before puting some bulb that will get warm. The poly will melt if exposed to hot!
-It may look (or feel) that you need to be so detailed and aware, but I discovered (at least in my case) is best to go wild on the cuting and ironing part, and more careful on the sanding part. Don't get frustrated trying to get perfection on early stages because poly is a material that needs some work.

That's it! it's not perfect but I hope you ejoyed it. I will be glad to answer any questions you may have. Thanks for reading!

 

Edited March 28, 2019 by Antigona

[KathieB]

Thank you for sharing this technique, Damaris. I've seen something similar using a stylus to outline bricks or stones, but the soldering iron makes much more robust stones. It never hurts to have several options when building.  

[zelda]

Thank you for the tutorial. Your buildings look wonderful.

[Antigona]

Thank you!

I want to point out that when using the soldering iron is better to be on an open area or well ventilated room (as well as wearing a mask if possible), because the fumes are (probably) toxic (and also they smell funny!).

[havanaholly]

Patricia King suggested using the stylus (similar tutorial in her book on dollshouse stoves & fireplaces), probably because of the fumes.  I love how your buildings turn out!

[KathieB]

I wonder if a wood burning tool might work as well as a soldering iron and be a bit easier to use. 

About a mask -- see the difference between a dust mask and a respirator here. 

FYI - extruded polystyrene is known as foam core board or contractor's foam board in the US.

 

[jbnmini]

Thanks for the tutorial!  Your stonework looks great!

[Antigona]

Thanks everybody! I'm pretty sure a wood burning tool would do the work as well, but maybe it would get dirt from the melted foam. I always use a mask like graffitti mask (for spray fumes). Thanks for the source Kathie!