Sandbag Fortress Building Instructions

This page will show how to use molds #222 and #340 to build this hilltop fortification.

You will need to cast molds #222 and #340 ten times each in order to build this model.

You can find complete information about the sandbag mold and the trench plank molds on our Tips & Tricks 32 page.

The Finished Sandbag Fortress
Click on the video to watch it on YouTube.

This video shows what this fortress will look like which may help you to decide if you want to attempt this project.

Finished Fortress

Printing and Transferring the Plan

You can find the plans to this project here.


This video describes the steps shown below, which includes how to assemble the printed plan pages and also transfer the design to layers of foam for cutting.

Assembling the Plan

First, print out the plans for this project. After you print all six pages, the second page will have a 6" line segment in the upper left. Be sure to measure this with a ruler to confirm that the print is actual size.

If it measures smaller than 6", then your plans will be the wrong size and the planks will not fit onto the walls. Be sure that your printer settings are not set to "fit to page". You want these plans to print actual size.


Pages 2, 3, 4 and 5 all fit together as one large print. When you lay these four pages together, you will notice there are vertical and horizontal lines running down the center.

Trim off the excess white edge next to these thin lines but do not trim off the thin black lines.

When lining up the top two pages, nip off one of the bottom corners so you can see to line up the center cross.


To line up the top edge of the paper, nip off the end of the vertical line so you can see where the line is on the page underneath.

With both the top and bottom lined up, tape the two pages together.


Also tape the bottom two pages together in this same manner.

To line up the top two pages with the bottom two pages, nip off the ends of horizontal lines so you can see the lines underneath.


After you assemble these four sheets, trim the excess paper off from around the plan.

You will have a large plan layout of the base as well as a smaller plan layout of the very top of the hill.

We will use these to transfer the outside shape of the hill onto 1" thick insulating foam.


For the base of the hill I am using 1/4" thick foam core board. It's a layer of foam sandwiched between two layers of thick paper and is very durable. You can find this at most office supply stores and is used for presentations and advertising displays.

If you can't find foam core board, then you can always use corrugated cardboard. It will not be as sturdy so be sure to use some very heavy cardboard if you can't find foam core.


The main body of the hill will be carved out of 1" thick insulating foam. It usually comes in pink or blue and you can usually find it at most lumberyards.

This is the stuff they use on the side of houses before they put siding on. If you live where the weather is nice all the time, then it may not be available in your area.


Tape the large drawing onto a 16" x 16" piece of foam core. Then use something sharp to poke holes around the outside of the design in every circle that has the letter "B" on it.

In this photo, I sharpened the tip of a paper clip using sand paper. You must use something that is sharp and fine such as a small sharp nail or the pointy end of a child's compass. I tried using a sharpened pencil but the foam core was too hard to puncture and the lead broke.


After you poke all of the holes, remove the paper and connect the dots using a ruler and a fine marker or pen.

You may want to keep the plan nearby so you can see which dots to connect. The base isn't too hard to figure out but it gets more difficult to determine which dots to connect on Level 1.

Cutting the Layers and Gluing on Planks

You will need to cast molds #222 and #340 ten times each in order to build this model.


This video describes the steps shown below, which includes the tools and method of cutting each of the foam layers. The 1/4" foam core is used for the base layer and 1" thick pink foam is used for all of the other layers.

Be extremely careful in cutting the foam so that you do not cut yourself.

Cutting the Layers

After you have drawn the outline of the base on foam core board, I'm going to use a hobby knife to cut it out.

Start by cutting exactly on the line halfway into the foam. Then lift up the foam and make the cut again, this time cutting completely through the foam.

Be sure you do not cut your fingers! Lifting up the foam will keep you from cutting your table top and also keep your knife from getting dull.


When cutting the 1" thick foam, I'm using an 18mm snap off utility knife. It's the kind of knife where you can snap the ends off when the blade gets dull.

This 18mm knife has a thicker longer blade than most simple snap off knives. I believe the common sized knives (like you find at Wal-Mart) would not be sturdy enough for the job. You'll need to go to a larger hardware store for one of these.


Be sure to cut straight up and down as much as possible. You want your walls to be 90 degrees to the table surface.

Cut down into the foam about 1/3 of the way down and follow the line as closely as possible.

Next make the same cut again going most of the way through the foam but not cutting all the way through.

If you are cutting an inside corner, try to not overcut the corners too much.


For the final cut, lift up the foam and cut all the way through. Keep your fingers out of the way of the knife when holding up the foam!

You can finish the inside cut by tilting the knife forward until it is cutting straight down into the foam. Then gently saw the foam until you cut all the way to the end of the line segment.

To glue the layers together, I like to use Aleene's Tacky glue. However, you can use most any PVA glue.


This is how the first layers will stack up. When stacking layer 2 on top of layer 1, line up the inside walls. The outside edges of the hill will not line up because they are meant to taper inwards towards the center. The inside walls should line up straight. Go ahead and glue these layers together.


While these layers are drying, go ahead and cut out layer 3. When marking out layer 3, you will notice that I drew lines where the sandbag enclosure will go.

Use a regular hobby knife to cut the square hole. Notice that the back side of the hole is angled back a bit but the other three sides are straight up and down.


Next you want to cut out the ramp blocks. You will find these in the center of the large plan. There is a triangular shaped piece and also a 2" square.

The smaller wedge shown here will end up being the ladder up to the sand bag enclosure on layer 3. Glue this into the spot shown here.

Be sure to glue this wedge all the way into the corner. The wall behind it should extend past the wedge by 1/4".


The 2" square is going to be split diagonally. Turn the square onto its side and use the knife to cut across from corner to corner. This will give you two angled ramp pieces.

Be very careful so you do not cut your fingers! I found it best to cut down halfway into the block, then turn the block over and cut the other half from the opposite side.


I have cut some slots into the ramp so that planks will fit into them. Each ramp will have two slots for planks spaced evenly.

Once these ramps are in place, add the final center plank by cutting off the tip of the top ramp. These planks will give your miniature a place to stand up while on the ramp.


Glue the planks onto the walls of the foam. Click on each of the photos below to see exactly where each large plank section goes.


Place layer 3 on top so the pointed ramp pokes through the square hole. Slide layer 3 as far forward as possible so the ramp pushes flat against the back side of the hole.

Glue two plank sections onto the bottom of layer 3 so they give the appearance of supporting the dirt roof over the trenches.

Be sure the plank section closest to you in the photo fits loosely over the trench (sand the ends if necessary). This section of trench will get smaller after painting.


Do not glue layer 3 on top of the hill!

Layer 3 will need to be removed so we can see inside of the hill. The reason we have glued the plank sections onto the bottom of layer 3 is to keep it lined up with the rest of the hill when cutting.

Carving the Hill


Now that you have the base layers glued together (and the glue is dry), we will set the top layer on and start carving the natural shape of the hill.

Be extremely careful in cutting the foam so that you do not cut yourself.

Cutting the Hills

A Quick Note Before Carving

I know this is scary. This step is probably the hardest part to get started on. You've spent hours casting pieces, drawing on foam, cutting foam and gluing the planks onto the walls. Now you have a knife in your hand and are paralyzed from the fear that you're going to end up destroying all of the work you have done.

I don't have an easy answer for you. Try your best to work past the fear and put that knife to the foam.

Start small. Take a corner off here and there. Cut away just a little to try and get one layer to flow into another layer. If you see an area that looks a bit too "humpy", carve it down a little and move on.

Your hill will not look exactly like mine no matter how closely you follow the video. That's OK because hills come in all kinds of odd shapes and sizes. If all you end up doing is to round off the sharp edges, your hill will still look good once you apply the dirt and grass to it.


Before we can carve the hill, we need to know where the sandbags will be placed. We do not want to cut away the land too far and have no flat area to glue our sandbags to.

Place the bottom row of sandbags down and draw around them with a marker.

You will notice that we have already drawn the lines around the square enclosure on top of the hill.


I started by carving away the top layer of foam. Using a sawing motion, gently cut away the sharp edges around the top.

Do not cut beyond the lines drawn with a marker! These lines indicate where your sandbags will go. If you cut beyond this point, your sandbags will not have a flat surface to set onto.


Click on the photo for a larger view.

Start carving away the outside edges of all of the layers below to remove the sharp edges. Try to get the hill to slope down naturally so you don't see any of the ridge lines from stacked layers. The face shown here will be sloped down gradually but the left and back sides will be more of a steep rock face.

Once again, do not cut beyond the lines drawn with a marker! These lines indicate where your sandbags will go. If you cut beyond this point, your sandbags will not have a flat surface to set onto.


For the steep areas, you want to cut some vertical grooves into the side of the hill. These are the areas we will end up putting a rock texture on.

Be sure to vary the depth, angle and width of these grooves for a more natural look.

As for the foam core base around the bottom of the hill, you will end up slicing it off while you are cutting the hill shape.


Since the foam core at the bottom is harder to cut, it's better to let the hill hang over the edge of a table top when sawing this foam core edge.

Be sure to round off all of the straight edges from when you transferred the original shape to the foam core.

Carving the Rock Face

You can find more specific instructions for this on our Tips & Tricks 31 page. I included the video here as well so you don't have to flip back and forth through web pages.


Rock Face Cutting Basics
The first video shows how to practice
cutting the rock face texture.

Cutting Rock Face on your Hill
The second video shows cutting the rock face
texture on the actual model.

Adding the Ladder and Planks


This video describes how to position the vertical planks.

It also shows cutting the top of the ladder ramp off and gluing it into the third layer as well as adding planks to the ladder area up to the sandbag enclosure.

Gluing on Planks

We will add the ladder up to the sandbag enclosure. First, you must cut off the top of the ramp that sticks up above layer 2. Try to get it as flat as possible.

Now glue this small wedge into the square hole on layer 3. It will end up in the same position it always was, only now it will be attached to layer 3.


Since we cut the ramp off, we will need a new way to get layer 3 to line up properly. Cut out a pyramid shape from the large empty area on layer 2 next to the ladder ramp.

Put it back into the hole, put glue on top of it and then position layer 3 back on top and let it dry.

Once dry, this pyramid shape will allow layer 3 to line up in the exact spot.


With this small ramp section now glued to layer 3, we can now add a couple of rungs to the ladder.

Use a hobby knife to cut a groove and glue a 1" plank into the groove. Also add another plank halfway down underneath it.

Using this same method, also add planks onto the main ramp below it.


When gluing on the vertical planks, be careful on the areas where layer 3 fits down.

You will need to shorten these planks by 1/4" in order for the top to fit properly.


Glue the single vertical planks onto the walls. Click on each of the photos below to see where I positioned each plank. If you run out of 1" long planks, simply snap a long plank in half. Be sure to glue the broken end down towards the floor.

Gluing on Sandbags and Making the Roof


This video shows how to make the roof of the sandbag enclosure and how to line the wooden support beams onto the sandbags below them.

It also shows the process for gluing the sandbags down onto the layout.

Gluing on the Sandbags

To make the roof, glue the plank pieces shown onto a piece of thin cardboard. Here I've use a discarded mailing box.

The reason I have used some of the 1/2" wide planks is because you will probably have run out of 1" wide planks at this point.

After gluing them, cut them out with a pair of scissors.


Flip the roof over and glue on the wooden braces underneath.

Use a ruler to be sure the center braces on the long side are in the exact center.

Move the braces away from the edge about the thickness of a single plank.


Click on the photo for a larger view.

This photo shows the exact placement of the wooden braces. All of the braces come in from the edge about the thickness of a single plank. If you put these braces all the way to the outside, they will not fall in center of the sandbag piles once you put the roof onto the sandbag enclosure.


Glue the sandbags shown on top of layer 3.

Try to vary the seams a little by putting different lengths down. You may even want to butt together straight sandbags for the corners instead of using the corner pieces like I have done.


Finish row 3 with the tapered sandbags.

Set the roof on and slide the sandbags so they fall directly under the wooden beams.


Glue on all of the remaining sandbags where ever you like.

When stacking rows of sandbags, try to vary the seams between the blocks.

Also make the tops of the sandbag wall uneven by using a variety of the smaller bag piles.

Painting and Masking

You can find more specific painting instructions including the color recipes on our Earth Tone Colors page.

Videos (Part 1)

Dark Brown Base Coat
The first video shows applying the base coat of
dark brown over the whole model.

Dry Brushing the Rock Face
The second video shows how to dry brush
the rock texture on the model.


You can find more specific painting instructions including the color recipes on our Earth Tone Colors page.

The base coat of paint is going to be dark brown. If you are using house paint, then you want to thin it with water, 1 part water to 2 parts paint.

Brush the paint over all parts of the model, including the sand bags and rock faces. Don't forget to also paint level 3 and the roof of the sandbag enclosure.

After painting, don't forget to wipe up the drips. After this coat of paint is dry, touch up the white spots and give the floor and foam one more coat of paint.


The rock faces are going to be dry brushed a medium brown-gray. To get this color, I'm mixing 1/2 medium brown from the Earth Tone Colors with 1/2 medium gray from the Castle Gray Colors.

You don't need much paint, just a couple of tablespoons. Dry brush this color onto all of the rock face surfaces.

For written instructions on dry brushing, be sure to look at the Dry Brushing Instructions.

Click on the photo for a larger view.

Videos (Part 2)

Medium Dry Brushing
This video shows applying the medium earth tone
colors to the planks and sandbags.

Bag and Plank Highlights
This video shows applying the highlights
to the planks and sandbags.


The next step is to dry brush the medium brown onto the wooden planks and sandbags. You can find the medium brown color on our Earth Tone Colors page. For written instructions on dry brushing, be sure to look at the Dry Brushing Instructions.

There will be some places where your rock faces may be close to your sandbags. In order to keep your dry brushing off of the rocks, you may have to mask some rock areas with masking tape. The blue colored paper tape from 3M is very good quality and a 2" wide roll will last you a long time.

The final highlight color for the planks will be a light peach color. The color is 2 parts medium brown, 3 parts white and 1 part red. Click on the photo for a larger view.


Before we dry brush the sandbags, we need to mask them off from the planks. Once again, I'm using the blue masking tape from 3M.

Any place you have sandbags on top of wood you will need to mask it. I was surprised at how many places needed masking. I had many small piles of bags sprinkled around for decoration.

You won't need to mask off bags if they are on normal ground. This area will have dirt and grass glued on later.


The highlight color for the sand bags is the regular light cream color found on the Earth Tone Colors page.

For written instructions on dry brushing, be sure to look at the Dry Brushing Instructions.

Click on the photo for a larger view.

Applying Dirt and Grass

The specific steps for applying the dirt and grass are on the Tips & Tricks 31 page. I have included only the videos here but be sure to visit this page to see the more complete set of instructions.


Using Real Dirt
This video shows how to prepare real dirt
and glue it onto your display.

Gluing on Ground Cover
This video shows how to glue
on the ground cover.

Sealing with Hairspray
This video shows how to seal
the grass and dirt onto your model.

Finished Photos

Click on the photos to see a larger version.

You can find complete information about the sandbag mold and the trench plank molds on our Tips & Tricks 32 page.

The German soldiers you see here are Bolt Action figures from Warlord Games. These soldiers are 28mm in scale and measure about 1 1/4" tall.

These soldiers were painted by GRG3D and he did a really nice job on them.