Scratchbuilt 1/72 Hürtgen Forest Bunker Diorama

A while ago I was asked to contribute an article to a new model making magazine. Sadly, the magazine never happened so I present the build article I wrote here. It’s interesting to go back over the build log of something I build a year ago. Even in 12 months I think my skills have noticeably improved. I’d still build it in the same way now, but I think the results would be a little better now.

Anyway. On with the build. The inspiration was reading about Hürtgen Forest during WW2. The Germans had plenty of time to dig into the woodland and gave the Americans a long drawn own, vicious fight.

I had a loose brief of ‘rocks and trees’ – here’s what I came up with.

A note on scale.

This dio is constructed in 1/72 scale. All the materials and techniques however, can can be employed for any scale. As this is a mostly natural scene, most measuring is done in place and by eye (I make it up as I go along). Just double up on any measurements mentioned for a close enough 1/35 (e.g. 3 inches becomes 6 inches). I always keep a figure or two nearby to gauge the size of things.

Bunker Construction

I’m using Extruded Polystyrene foam as the bulk of the construction material for this project. It comes in huge sheets from builders merchants in several densities. I actually pulled mine out of a skip outside a house that was being done up. Pink and blue is the most common, blue being more dense than pink.

I started with the roof of the bunker roof by cutting a strip of 1 inch thick foam into a 3 inch wide strip and shaved off the corners. I use cheap retractable knives for this. The extra long blade comes in handy. Make sure the blade is sharp or it’ll snag on the foam and won’t leave a clean cut. You can use a hot wire cutter, but these simple cuts are easier and less faff with a blade.

Next, I marked a ¼ inch line along the top edges of the bunker roof and sliced off the diagonal. Take your time and if you go off the lines, back up and go again slowly. You can cover up any errors later.

Now to give the foam a bit of texture. These huge slabs of concrete were poured gradually, a few feet at a time and this leaves a ridged texture along the side of the bunker walls. I replicate this by dragging a blunted cocktail stick along the side.

I currently have no idea how big the dio is going to be, or how big the bunker needs to be to fit on the dio so I’ve made it extra long for now.

On to the walls. I used ¼ inch thick foam and used a figure to roughly mark out the sides of the bunker. I use a t-square to square up the corners and to keep things straight. Once this had been cut to size against the roof, I used it as a template for the 2nd side.

The hexagonal front means there’s a tricky join around the front. I chamfered it by eye. Any gaps can be filled later.

And assembled the front walls.

Once I’d got all the walls and bevels lined up (don’t be afraid to throw a piece away and start again) and again textured them with a cocktail stick.

Time to glue the bits together. Regular woodworking glue (PVA) is fine but here I’m using Titebond 2 which has a lot more instant grab and hold than PVA and has good gap filling qualities. The only downside is that it doesn’t dry clear – not an issue in this case as the whole thing will be covered and painted later.

I use berry pins to hold pieces in place while they glue. They work best when driven in at an angle as this pulls the two pieces together a little and reduces the chances of the pieces shifting. Masking tape can also be used to clamp awkward pieces together if needed. The pink spacer in the middle is just held in place by friction and keeps the walls vertical and perpendicular to each other while the glue dries.

As you’ll be able to see (a little) inside the bunker, I added a back wall and door to give a bit of visual interest.

I waited for the this to dry and then repeated the process for the bottom wall.

With the bunker shell complete I could now start to size up the base and get a feel for the size of the project.

A rocky path…

I cut a base from 1 inch foam roughly to size and dry fitted the bunker jutting out to cover a bend in a forest track.

Next I began building up the rocky slopes around the bunker. This is a great way to use up any offcuts. I wanted a natural path from the ground level to the top of the bunker so I stacked various random chunks of foam until I got something that looked right. Everything is dry fitted at the moment while I experiment with placement. Hold everything in place with pins otherwise you’ll be forever knocking stuff around.

Once I was happy with the overall placement I glued the piles together. The bunker is still dry fitted – I need to be able to get inside to paint it later. I used a sharp scalpel to carve details into the steps and rocks. A google image search is invaluable as reference material here.

I distressed the rocks along the back with a craft knife. A criss cross of vertical and horizontal cuts with the knife and dragging the blade edge diagonally over the surface leaves it looking like this:

Now the major components are ready to glue down, but first I blacked out the inside of the bunker with acrylic paint. You can paint acrylics directly onto the foam but enamel paints will melt it!

Next I got brutal with the landscape and used a broken chunk of concrete to impress texture into the rocks and ground. Vary which side and rotation as you press in the textures. The human eye is *very* good at spotting repeated patterns where they aren’t expected and this will drag the viewer out of the scene.

Bashing it with a lump of concrete invariably caused some areas to warp and move so I filled any gaps with ready mixed polyfilla, applied straight from the tub with a spatula. No need to be too neat and tidy, this is nature after all…

Once this had dried, I sealed the whole piece with watered down pva (about a 50:50 mix) with a drop of dish soap to help it soak into the cracks. This is mainly a preventative measure to stop any enamel based paints I might use later from eating into the foam.

Once the PVA had dried I watered down the ready mixed polyfilla and applied it with a rough brush, dragging it along the edges of the bunker horizontally to build on the layered concrete texture we’re after. Polyfilla wants to dry flat so keep working it as it dries. Do the big textures first and fainter textures when it’s almost dry.

Using the same mix of polyfilla and water I stippled the roof by jabbing the pollyfilla with a large dry brush.

I used a combination of stippling and dragging to texture the remainder of the base. Again, keep working it as it dries.

Bringing it to life….

I began by giving the whole piece an undercoat of UMP Grey Primer through my trusty H&S Ultra airbrush. A couple of light coats were left to dry under the heat lamps.

Next I pre shaded all the nooks and crannies with tamiya flat black (XF-1) thinned with UMP airbrush thinners.

Next I mixed up a base concrete colour with tamiya light grey and a smidge of deck tan to get a kind of warm grey. I sprayed this on, allowing some of the preshading to blend through.

I sprayed the rocks with the light grey I used for the concrete, focussing on the tops of the rocks, again allowing the preshade to come through.

I mixed up a dilute wash of tamiya flat black and water and applied it to the rocks. The wash sinks into the nooks and crannies adding definition and shape.

Once the wash had dried, I came back with the same light grey and lightly drybrushed the very edges of the rocks using a large soft makeup brush. I wipe practically all the paint from the brush so as to only leave a hint.

I made up a muddy brown wash and applied it to the bunker. That’s the bulk of the painting done for the base!

I used garden compost soil, bits of lichen cut up fine, cork bits, tiny twigs, clumping flock, scatter flocks and static flock fibres to mix up some floor litter. You can buy ready blended mixes too but this is a great way to use up any flock bits you have left over.

Those are actually 1/35 scale leaves (the seeds from a catkin) but I’m only using a few and nature sometimes throws up a few mutants so they don’t look out of scale.

I brushed undiluted PVA onto the dio where I wanted the flock and sprinkled it on between my thumb and forefinger. Allow it to pile and fall away naturally. Don’t worry if bits fall where there’s no PVA, we’ll fix those errant patches in place later.

Focus on the top of rocks and places where you want to hide a join.

I mixed up some more 50:50 Water/PVA + dishsoap and used a pipette to drench the litter. This fixes it in place. It’s *very* easy to smudge the flock at this time, so keep your sleeves out of the way. I left it to dry overnight. By morning it’s rock solid.

The next day I laid down a layer of undiluted pva along the ground and used pinches of static flock fibre dabbed into the PVA to form a grassy forest path through the middle.

It looks a bit unkempt, but well remove any excess once the glue has dried.

While the PVA was setting up, I used a large brush to scrape tracks into the grass, the pva causes the grass to clump quite naturally around the edges of tracks.

Once the grass had dried, I removed the access and used a stiff brush to fluff up the fibers.

I ground up some of the potting compost I used for the scatter into a fine dust but left a few chunks in for texture. I filled the tracks with pva and sprinkled it on. I ran a few wheels through it before it dried to pick up a few tire tracks.

It looks a bit astro turf at the moment and the tracks stand out like a saw thumb.

Using an old brush, I mixed up some dilute burned umber craft acrylic (craft acrylic is way cheaper than model acrylics, I try to use them whenever I can on terrain as you tend to need a lot of it) and jabbed it into and around the tracks.

While this was wet, I went back with some thicker burnt umber and stippled it along the tracks. Don’t use your best brushes for this!

Keep working and blending the tracks as it dries were after churned up mud and grass.

I used the same watery brown mix on the stones, drawing it along cracks and around the edges of the leaf litter. The brown represents dirt washing away so needs to follow a natural course.

I used an earthy green mix, this time, focusing on the bottom edges of things and growing it up and along surfaces to represent mould and mildew types of build up. I extended this onto the bunker too.

Keep stepping back to ensure you’re getting a good balance of tones throughout the rocks.

It’s not just trees that grow in a forest, so it’s time to add a bit of flora to the ground work. I started with some clumping flock bushes – these I bought on ebay for a few pounds. A little is better than too much otherwise those bright colours will dominate the scene.

I broke the flock into small clumps and and stuffed it into nooks and crannies with a blob of superglue.

I used pre-made static grass clumps to add a bit of variety to the ground cover.

And rubberised horsehair to form a small bramble patch.

Sprucing up the trees.

There was enough groundwork down now to start thinking about some trees. I opted for some Woodland Scenics pine trees I had in my stash. Out of the box, they look ok for background trees, but these would be front and center and needed some TLC to bring them up to scratch. I assembled my materials. The brown stuff is coconut fibres pulled from a hanging basket liner.

Once I’d bent the tree armatures into place, I chopped up the coconut fibers using a pair of scissors. I was aiming for pieces about ¼ inch long but a few over/under sized is good.

I used white putty to add additional bark texture and burls to the trunks with a cocktail stick. It doesn’t take long to dry.

I sprayed the armatures with spray glue and sprinkled on the coconut fibers.

Once the glue had dried I knocked off any excess fibres and undercoated them to seal everything in.

I sprayed them all with Tamiya brown and gave them a light drybrush with deck tan.

I then dabbed gel superglue over the tops of some of the branches and squeezed the clumping flock foliage onto the trees. Expect to get clumping flock super glued to your fingers. Or wear gloves.

I used one of the small armatures as a fallen log. I flattened it and sprinkled some flock on the top surfaces to represent moss.

I originally planned to have some of the trees on the hillside around the bunker, but that side was already looking very busy so decided to clumped them up on the other side to give a view through the trees towards the bunker. Speaking of the bunker, it was looking way too bright and clean so I toned down the concrete with a very thin black wash.

I use enamel pigments to add mould build up. I let it mainly dry and then feathered the edges with odourless thinners.

I built a couple of sections of fence from plastruct rod and florists wire. I used a pin vice to drill the mounting holes through the rod.

I roughed up the plastruct with the edge of a razor saw. This is a quick way to add a wood texture and looks great with a bit of paint and a wash.

I used life color weathered wood for the posts and AK rust for the wires.

I test fitted the fence along with the trees.

Sandbag Bunker

The roof of the bunker was a massive, boring, flat open space and definitely needed something to fill it. I thought a small artillery piece would work but needed some form or protection.

I used white milliput (as it’s what I had to hand) to create a square sandbags. First by rolling them into a long sausage then flattening them with my finger. I used a craft knife score the bag detail into the clay.

The roof supports are plastic rod, textured with a razor saw like the fence posts.

Once the bags had dried, I cut a roof from textured plastic sheet and distressed it with a craft knife and by bending it between my fingers. I was planning on covering most of the roof with sandbags so no need to go detail mad.

I covered the roof in sandbags using the same technique as the walls. Any spare bits of clay can be used up to fill unintentional gaps.

I undercoated them with UMP black primer.

I drybrushed tamiya desert sand over the sandbags as a base coat.

And then gave the whole piece a heavy wash with UMP dark dirt. Clay wash. Note: Usually you would prepare your piece with a clear coat before using UMP, but in this case, I wouldn’t be washing it off and the matt surface of the paint helps the UMP to blend naturally with the base coat.

I roughly cleaned the top of the bags with water on a cotton bud to take off a bit of the UMP. You have to work pretty quick or the UMP will stain permanently and won’t come off!

Camo Nets

The sandbags bunker was looking a bit obvious perched on top of the bunker so it was time to camouflage it.

I started with some cheap stretch bandage. I cut it into squares and then teased apart the threads with my fingers. This is a fiddly job and took a couple of attempts before I got the result I was after.

I rolled up the tarps and used cotton to tie the ends of the rolls to stop them unravelling.

I soaked all the pieces of netting in green acrylic paint and once they were dry I attached them to the sandbag bunker with superglue.

I used a similar mix of flocks as the ground scatter on the netting. I wanted it to look like it’d been there for a while. I fixed the flock in place using watered down PVA again.

All Done

A last bit of tidying round and I took it outside for some daylight shots:


[amazon_link asins=’B00GSX3U6O’ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’c3a75073-4dde-11e7-9b6a-af733165ca53′] [amazon_link asins=’B00GLZ25BK’ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’f71fbc49-4dde-11e7-904c-3917a05b0d27′]
[amazon_link asins=’B00EO6TC0U’ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’e1e1008d-8324-11e7-ba70-0d72892784a7′]
[amazon_link asins=’B002CNEWAM’ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’57ba09ba-e3c2-11e7-a7f6-0d04fb196d04′]
[amazon_link asins=’B00KAFKO56′ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’873e0ab1-e3c2-11e7-9a49-638a440dbdd7′] [amazon_link asins=’B005717NXE’ template=’ProductAd’ store=’richbuilds-21′ marketplace=’UK’ link_id=’03dfb68a-e3c3-11e7-8777-47f2a50d7f53′]