HG Hashmal Seam Line Removal and Scribing: Part 2 of the Custom Gunpla Build Series

TL;DR: This second part of the HG Hashmal Custom Gunpla Build Series focuses on refining the surface of the kit through seam line removal and custom scribing. After completing the straight build, the next step was to remove visible plastic joins, smooth the armour surfaces, and add new panel line detail to the wings, legs, and armour sections. These subtle upgrades helped the HG Hashmal look cleaner, sharper, and more premium before painting began.

Every custom Gunpla build reaches a point where the kit starts to feel less like a snap-fit model and more like a finished display piece.

For the HG Hashmal, that moment began with surface refinement.

After the straight build was complete, the next stage focused on removing seam lines and adding new scribed detail. The goal was not extreme customisation, heavy weathering, or changing the entire identity of the kit. Instead, this stage was about refinement: making the Hashmal look cleaner, sharper, and more believable while staying true to the original Mobile Armour design.

The HG Hashmal already has a strong silhouette, wide wingspan, and aggressive mechanical shape. But like many High Grade Gunpla kits, the straight build still had areas that looked obviously plastic. Visible joins, plain armour sections, and large smooth surfaces all created opportunities for improvement.

This is where seam line removal and scribing made a major difference.

Why Seam Line Removal Matters on High Grade Gunpla

The first step in the refinement process was seam line removal.

High Grade Gunpla kits often have visible seam lines where two plastic parts meet. Sometimes these joins are easy to ignore, but on a sleek design like the HG Hashmal, they can interrupt the clean shapes that make the Mobile Armour look so striking.

The legs and armour sections were especially important areas to check. These parts have long, sharp shapes that give the Hashmal its predatory look, so any unwanted seam lines can distract from the overall silhouette.

Removing seam lines may seem like a small step, but it can completely change the final presentation of a Gunpla build.

Instead of looking like separate plastic shells clipped together, the armour begins to feel more like one continuous manufactured machine. The effect is subtle, but once you notice it, it makes the entire kit look more polished.

Identifying Which Seam Lines to Remove

Before sanding or cementing anything, the first step was deciding which lines should actually be removed.

This part is important because not every line on a Gunpla kit is a seam line. Some lines are intentional panel separations, armour breaks, or mechanical design details. Removing the wrong line can make the kit look less detailed instead of more refined.

For the HG Hashmal, the focus stayed on obvious joins that broke the surface or interrupted the silhouette. Natural panel separations were left alone because they helped support the mechanical design of the kit.

This is one of the most important habits in Gunpla customisation: study the kit before changing it.

A good custom build does not remove detail for the sake of making everything smooth. It keeps the useful design language and only cleans up the areas that make the model look unfinished.

Smoothing the HG Hashmal Armour Surfaces

Once the unwanted seam lines were identified, the parts were cemented together and left to cure fully.

Patience matters at this stage.

If the cement has not cured properly, sanding too early can affect the alignment of the parts and create more surface problems later. Waiting gives the plastic time to bond properly, which makes the seam easier to level cleanly.

After curing, sanding began with a coarser grit to remove the raised seam and smooth the join. From there, the surface was gradually refined with finer grits to restore a clean finish.

This step takes time, especially on white armour. White plastic can make imperfections easier to see under direct light, so the surface needs to be carefully checked from different angles.

But once the seam line removal is complete, the difference is dramatic.

The HG Hashmal immediately starts to look less like a basic snap-build and more like a finished custom model.

Adding New Panel Lines with Scribing

With the surfaces cleaned up, the next stage was custom scribing.

This became one of the biggest visual upgrades in the entire HG Hashmal custom build.

The Hashmal has several large smooth armour sections, especially across the wings and legs. These areas already look impressive because of their shape, but they can feel too plain without additional surface detail.

Rather than relying only on the existing moulded panel lines, the goal was to add new panel separations that made the design feel more layered and mechanical.

The key was restraint.

The aim was not to overcrowd the kit with random lines. The new scribed details needed to look like they had always belonged there.

Planning the Custom Scribed Details

Before cutting new lines into the plastic, I studied the flow of the armour and looked at where extra detail would feel natural.

The wings became the main focus because they are one of the HG Hashmal’s most recognisable features. Their wide surfaces create strong visual impact, but they also leave a lot of empty space in a straight build.

Adding new panel divisions helped break up those large flat areas while keeping the clean, aggressive silhouette intact.

The legs also benefited heavily from scribing.

Their long, blade-like design already gives the Hashmal a sense of movement, but carefully placed scribed lines made the armour feel sharper and more engineered. Instead of looking like plain moulded plastic, the legs started to feel more like layered mechanical armour.

This is where custom scribing becomes more than just adding lines. It helps guide the viewer’s eye and makes the model feel more intentional.

Why Scribing Takes Patience

Scribing is one of those Gunpla customisation techniques where rushing almost always shows.

A crooked or uneven panel line is easy to spot, especially on white armour. For this reason, each line needs to be built up slowly with light, controlled passes rather than forced in one go.

Gradually deepening the line helps keep the edges clean and reduces the risk of slipping across the surface.

This stage takes patience, but it is also one of the most satisfying parts of a custom Gunpla build.

Painting can change the finish of a kit, but scribing changes the design itself. It creates the illusion that the model was always meant to have those extra details, as if they were part of the original engineering.

That was the goal with the HG Hashmal.

Not to add detail for the sake of detail, but to enhance what was already there.

How Seam Line Removal and Scribing Changed the Build

By the end of this stage, the HG Hashmal already felt completely different.

The smoother armour surfaces from seam line removal made the kit look cleaner and more refined. The new scribed panel lines added sharper definition and helped break up the larger white armour sections.

Even before painting, the build had started to look more premium.

It no longer looked like a straight build.

It looked like a project.

That is one of the most rewarding moments in any custom Gunpla build. It is the point where the kit begins to feel personal, where the small decisions start adding up, and where the model begins becoming something unique.

Key Takeaways

• The HG Hashmal benefits strongly from seam line removal because its sleek Mobile Armour design relies on clean armour shapes and sharp surfaces.

• Not every visible line should be removed. Some lines are intentional panel separations, so it is important to study the kit before sanding or filling anything.

• Custom scribing added new mechanical detail to the HG Hashmal’s wings, legs, and armour sections. These details helped break up large plain surfaces and made the kit feel more layered and premium.

• Subtle surface refinement can make a major difference before paint is even applied. Seam line removal and scribing helped transform the HG Hashmal from a straight build into a true custom Gunpla project.

FAQs About Seam Line Removal and Scribing Gunpla

What is seam line removal in Gunpla?

Seam line removal is the process of removing visible joins where two plastic parts meet. This usually involves cementing the parts together, allowing them to cure, then sanding the seam until the surface looks smooth and continuous.

Why remove seam lines on High Grade Gunpla kits?

Many High Grade Gunpla kits have visible seam lines because of the way their parts are moulded. Removing these lines can make the model look cleaner, more realistic, and less like a basic plastic snap-build.

Does the HG Hashmal need seam line removal?

The HG Hashmal looks impressive as a straight build, but it benefits from seam line removal in areas where visible joins interrupt the sleek armour shapes. The legs and armour sections are especially worth checking during a custom build.

What is scribing in Gunpla customisation?

Scribing is the process of adding new recessed panel lines into the plastic surface of a model kit. These lines can create extra armour separation, mechanical detail, and visual depth.

Why add new panel lines to the HG Hashmal?

The HG Hashmal has large smooth armour sections, especially on the wings and legs. Adding new panel lines helps break up these plain areas and gives the model a more detailed, engineered appearance.

Is scribing good for beginner Gunpla customisation?

Scribing can be beginner-friendly if done slowly and carefully. It is best to start with simple straight lines, use light passes, and practise on spare plastic before working on visible armour parts.

What tools do you need for Gunpla seam line removal?

Common tools for seam line removal include plastic cement, sanding sticks or sanding sponges, hobby files, and different sanding grits. The goal is to bond the parts, level the seam, and restore a smooth surface.

What tools do you need for Gunpla scribing?

Gunpla scribing usually requires a scriber or panel line chisel, guide tape, a hobby ruler, and patience. Guide tape is especially helpful for keeping new panel lines straight and controlled.

How do you avoid over-detailing a Gunpla kit?

The best way to avoid over-detailing is to follow the existing design language of the kit. Add lines where they support the shape, flow, or mechanical structure of the model rather than placing detail randomly.

Do you need to scribe before painting Gunpla?

Yes, scribing is usually done before painting. This allows the new panel lines to be cleaned, sanded, primed, painted, and panel lined as part of the final finish.

Final Thoughts

The seam line removal and scribing stage was where the HG Hashmal custom build really started to change.

The straight build showed the kit’s strong foundation, but this stage helped refine the surface and sharpen the overall design. Removing unwanted seams made the armour look cleaner, while custom scribing added new depth to the wings, legs, and large armour sections.

These changes were subtle, but they made the HG Hashmal feel more intentional and more display-ready before paint was even applied.

Missed the first stage of the build? Read Part 1: HG Hashmal Straight Build Review to see where this custom Gunpla project started.

In the next blog, I’ll cover the painting stage, including subtle colour changes, soft shading, and cleaner detail separation, and how those steps transformed the HG Hashmal from a refined custom build into a true display piece.

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