Building a Martian Gunpla Diorama Base: Barbatos vs Hashmal Part 2

TL;DR: In Part 2 of this Gunpla diorama series, I’m carving and shaping the Martian battlefield base inspired by the clash between Gundam Barbatos and Hashmal from Mobile Suit Gundam: Iron-Blooded Orphans. Using XPS foam, hobby knives, sculpting tools, texture paste, sand, gravel, and rubble, the goal is to turn simple foam shapes into a rough, damaged battlefield full of movement, impact, and story.

Once the planning was done, it was time for one of the most satisfying parts of the build.

Taking a few simple pieces of foam and turning them into something that actually looked like the surface of Mars.

This is the stage where the project stops feeling like an idea and starts becoming real. In Part 1, I focused on the concept, layout, and overall story of the diorama. For Part 2, the goal was to start building that world physically by cutting, layering, carving, and texturing the battlefield.

The aim for this diorama was to recreate the brutal clash between Gundam Barbatos and Hashmal from Mobile Suit Gundam: Iron-Blooded Orphans.

That meant the terrain couldn’t feel clean or controlled. It needed to feel harsh, damaged, and unstable, like the aftermath of violence had already been written into the ground itself.

No clean surfaces. No perfect lines.

Just chaos.

If you’re planning a scene like this, the kit choice matters just as much as the base. The pose, scale, and silhouette of the mobile suit all help shape the story you’re trying to tell.

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Building the Main Cliff Sections

I started with the main cliff sections.

Using XPS insulation foam, I cut rough block shapes that would become the elevated rock walls around the back of the circular base. I wasn’t aiming for symmetry. In fact, the less balanced it looked, the better.

Natural terrain is messy. Perfect shapes can immediately make a diorama feel artificial, especially when the goal is to create a dry, rocky Martian battlefield.

The rear walls were designed to create a canyon-like frame around the centre of the scene. I wanted the terrain to feel like Barbatos had been forced into a brutal confrontation zone, surrounded by towering rock, broken ground, and unstable terrain.

Instead of using one large solid piece, I layered multiple foam sections together.

This helped create natural depth and gave the cliffs a more believable geological feel. Real rock formations aren’t flat slabs. They break, collapse, shift, and form in uneven layers.

Stacking the foam allowed me to mimic that look without needing overly complex sculpting.

Every angle mattered.

The open front of the base was left intentionally clear to preserve visibility, while the raised rear sections helped create depth and tension. I wanted the battlefield to feel enclosed without making the scene feel crowded.

Early foam cliff sections being layered and positioned around the rear of the circular base to create a canyon-like battlefield frame.

Carving the Foam into Rock

Once the major shapes were in place, it was time to destroy them. This is where the foam starts becoming rock.

Using hobby knives, sculpting tools, and rough wire brushes, I worked into the surfaces to remove the smooth factory finish. Sharp edges were broken down, flat faces were damaged, and cracks were carved directly into the foam.

The goal wasn’t to make the cliffs look neat. It was to make them look worn, fractured, and exposed.

I focused on creating layers of erosion rather than simple random cuts. Rock faces need direction. Gravity leaves marks. Time creates patterns.

Instead of carving aimlessly, I tried to imagine how the cliffs would naturally break apart after years of exposure, impact, and battle damage.

That mindset helped guide the carving process.

Long vertical cuts helped suggest weathering and erosion, while broken edges and rough gouges made the cliffs feel more damaged. Smaller scratches and surface marks added extra variation so the rock didn’t feel too smooth or repetitive.

This stage can look messy while it’s happening, but that’s part of the process.

Terrain building rewards roughness. The more I carved into the foam, the more the base started to lose its artificial shape and feel like part of an actual battlefield.

Close-up of the carved cliff faces, showing rough cuts, fractured foam, and early rock texture before painting.

Shaping the Broken Martian Ground

The ground surface needed just as much attention as the cliffs.

Rather than leaving it flat, I added uneven terrain, shallow craters, broken earth patterns, and scattered debris zones. Since this scene represents the chaos of Barbatos facing Hashmal, I wanted the battlefield to look like it had already been scarred by conflict.

The central area became especially important.

This would be the visual impact zone, the place where the confrontation feels strongest. Even without the kits standing there yet, the base needed to suggest weight, movement, and destruction.

I created fractured surface details and rough texture across the centre of the base to make it feel like something violent had already happened there.

That storytelling matters.

A good diorama shouldn’t need too much explanation. The terrain itself should hint at the narrative. Before Barbatos or Hashmal are added, the base should already feel like a place where a battle belongs.

The lower front area was kept more open so the viewer’s eye could move naturally into the scene. The raised rear cliffs added drama, while the broken ground helped pull everything together.

The balance was important. Too much texture everywhere can make the scene feel busy. Too little texture can make it feel unfinished. I wanted the surface to look damaged, but still leave enough open space for the models to stand clearly.

The base layout after carving, with rough cliffs, broken ground, and an open central space prepared for the Barbatos vs Hashmal confrontation.

This is also where simple hobby materials do most of the heavy lifting. Foam, texture paste, glue, sand, gravel, and basic carving tools can completely transform a plain base into something with atmosphere, weight, and story.

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Blending the Terrain with Texture Paste

Once the carving was complete, I moved on to blending everything together.

This is where texture paste became essential.

Foam layers can leave obvious seams, and nothing ruins realism faster than visible construction lines. Texture paste helped smooth those transitions while also adding rough natural surface detail.

It also gave the ground a heavier, more realistic texture that paint alone could never achieve.

I applied the texture paste across the joins between foam pieces, around the base of the cliffs, and across sections of the ground where I wanted extra roughness. This helped make the terrain feel like one connected environment rather than separate pieces glued together.

The paste also created a better surface for paint later.

Bare foam can sometimes feel too smooth or too light, especially when trying to recreate rocky terrain. Texture paste adds grip, weight, and irregularity, which all help the final paint and weathering stages look more convincing.

At this point, the base started to feel much more unified.

The cliffs no longer looked like stacked foam blocks. The ground no longer looked like a plain base. Everything started to merge into one harsh Martian battlefield.

Adding Sand, Gravel, and Rubble

To push the realism further, I added sand, small gravel, and rubble around the base.

Loose debris makes a huge difference.

It breaks up flat surfaces, adds scale, and helps sell the illusion that these are massive cliffs instead of carved foam. Small details like this are often what make the final build feel convincing.

I focused the debris around the base of the rock walls, along broken ground sections, and near areas that looked like they had collapsed or been damaged.

This helped the terrain feel more natural.

Rocks don’t just stop at the edge of a cliff. They crumble, scatter, and collect in uneven piles. Adding gravel and sand helped show the connection between the cliffs and the ground.

The trick is not to make it too even.

If the sand and gravel are spread perfectly across the whole base, it can start to look artificial again. I tried to keep the debris clustered in areas where it made sense, leaving some surfaces more open and others more heavily damaged.

This was the moment the project changed. It stopped looking like insulation foam and started looking like terrain.

Honestly, that transformation is one of my favourite parts of building dioramas. There’s something incredibly satisfying about seeing simple materials become something believable.

It reminds you that display work doesn’t need expensive tools. It just needs patience, vision, and a willingness to make a mess.

Why Texture Is So Important in Diorama Building

Texture is what makes terrain believable.

A painted surface can look good, but without physical variation underneath it, the effect often feels flat. For a Martian battlefield, the surface needed to catch drybrushing, washes, pigments, and shadows later on.

That meant the texture had to do some of the work before painting even began.

The carved foam created the larger rock shapes. The texture paste added rough surface variation. The sand and gravel brought in smaller natural details.

Each layer had a different job.

Together, they helped build the illusion of scale.

This is especially important in Gunpla dioramas because the mobile suits are large, mechanical subjects. If the ground is too smooth or too simple, the models can feel disconnected from the scene. But when the terrain has cracks, rubble, dust, and broken surfaces, the mobile suits feel heavier and more grounded.

For Barbatos and Hashmal, that sense of weight was essential.

This battle needed to feel brutal. The base had to support that.

Key Takeaways

• The carving stage is where the diorama starts to feel real. Simple XPS foam can become convincing rocky terrain with enough cutting, layering, and surface damage.

• Layering foam sections helped create more believable cliff faces and gave the rear of the base a stronger sense of depth.

• The ground surface needed to support the story of the scene, so I added uneven terrain, shallow craters, fractured details, and debris zones to suggest movement and destruction.

• Texture paste was essential for blending seams, roughening surfaces, and making the terrain feel like one connected battlefield.

• Sand, gravel, and rubble helped add scale and realism, especially around the cliffs and broken ground.

• Most importantly, this stage was about controlled chaos. The base needed to feel damaged, unstable, and natural before any paint or weathering was added.

Frequently Asked Questions

Can XPS foam really look like rock?

Yes. XPS foam is one of the best materials for creating rocky terrain because it is easy to cut, carve, layer, and texture. Once the smooth surface is damaged and painted, it can look very convincing.

What tools can you use to carve foam terrain?

Hobby knives, sculpting tools, wire brushes, toothpicks, and even rough stones can be used to shape and texture foam. The goal is to remove the smooth surface and create natural variation.

Why layer foam instead of using one solid block?

Layering foam helps create depth and makes the terrain look more natural. Real rock formations often have visible layers, cracks, and uneven shapes, so stacked foam can help recreate that effect.

What does texture paste do in a diorama?

Texture paste helps blend seams, cover construction lines, and add rough surface detail. It also gives paint, washes, drybrushing, and pigments a better surface to work with.

Should the terrain be perfectly smooth before painting?

No. For rocky or battlefield terrain, imperfections are helpful. Cracks, rough areas, broken edges, and debris all make the final scene feel more realistic.

When should sand and gravel be added?

Sand and gravel are usually added after the main terrain has been carved and glued in place. They work best as smaller surface details that help break up flat areas and add scale.

Final Thoughts

This stage was all about turning the idea into something physical.

The planning from Part 1 gave the diorama its direction, but the carving and texture work gave it shape. By layering foam, cutting into the cliff faces, damaging the ground, and adding texture paste, sand, gravel, and rubble, the battlefield finally started to feel like a real place.

• The cliffs stood heavy around the back of the base.
• The broken Martian ground stretched across the centre.
• The scene felt harsh, dry, and dangerous, exactly what I wanted for the Barbatos and Hashmal confrontation.

But even with all the shaping and texture complete, it still wasn’t finished.

At this stage, it was still raw terrain. The real transformation would come next. 

Because paint is where the battlefield truly comes alive.

In the next blog, I’ll be covering the final stage: painting, weathering, and bringing the red dust of Mars to life so this battlefield finally feels worthy of Barbatos and Hashmal.

Missed Part 1? Read it here: Building a Martian Gunpla Diorama Base: Barbatos vs Hashmal Part 1

For more tips and tricks, follow me on socials @rosie_custom_gunpla