Custom Build: FM 1/100 GAT-X255 Forbidden Blue Build By Yasutaka Tanaka / 田中康貴 (HJWEB Custom build)

In the field of Gundam model customization, the construction of Forbidden Blue is an impressive feat. Inspired by Full Mechanics' Forbidden Gundam, this project began with a vision: What if Forbidden Blue was designed with the precise precision and standards of a FM 1/100 kit? This notion drove the effort, aided by the vivid picture of the Gundam setting.

Base Kit

The GAT-X252 Forbidden Gundam was adapted for the Earth Alliance's first amphibious mobile suit, the Forbidden Blue, by adding new weaponry, sensors, and propulsion systems. Its arm-mounted machine guns and CIWS weapons are rendered useless underwater, although they are stored for use in the event that the mobile suit surfaced again. Forbidden Blue has torpedo launchers and a phonon maser cannon in place of the original Forbidden's plasma cannon and railguns. The hefty scythe becomes four retractable weapons that are interwoven into the shields, while the main handheld weapon becomes a trident. To improve its swimming abilities, a tail extension equipped with several gadgets is fastened to the backpack.
The "Geschmeidig Panzer" energy deflection armor and Trans-Phase armor are retained by Forbidden Blue, who can also morph into a fast-moving assault mode. In contrast to the Forbidden Gundam, the energy deflection armor in Forbidden Blue is primarily used as pressure hulls and for underwater navigation. Forbidden Blue was created in four units, and the knowledge gathered from these units helped to design the GAT-706S Deep Forbidden and, later, the GAT-707E Forbidden Vortex.

THE BUILD Body Customization 

  The Forbidden Gundam's transition into the Forbidden Blue was a laborious operation. Each joint's bellows molds were meticulously rebuilt using plastic plate work, demonstrating the craftsman's ability and attention to detail. Concerns about the abdomen's thinness, the side armor's tip thickness, the ankle armor's vertical width, and the surrounding space were addressed. This was accomplished by adding plastic plates to increase the volume while maintaining a harmonious balance with the Gundam's heavy armored array. 

The Backpack Modification

  The backpack of the kit underwent considerable changes, including the shape and relocation of numerous pieces. The primary work used plastic plates, but the propeller's base was creatively constructed from a resin block known as chemical wood. This material, recognized for its ease of cutting and filing, made an outstanding prototype before being recreated in resin. The tail exterior, made of a plastic box assembly, demonstrates the ability to duplicate its unfolded form through the use of joint pieces. 

Armor Array

  When it comes to the armor array, the design idea was twofold: maintain pressure resistance while increasing visual impact. Drawing inspiration from the Geschmeidig Panzer kit, the goal was to construct an array that was both accurate to the original design and visually appealing. The markings, inspired by the setting's horseshoe crab iconography, were made from chemical wood and used as prototypes before being duplicated in resin. The spikes' base, a tribute to the Nidshogg, had a deployment mechanism made of plastic plates and pipes, demonstrating a balance of aesthetics and utility.


Torpedo pod design was an exercise in variety and detail, resulting in two separate types: primary and variations. This approach used a combination of plastic materials, commercially available parts, and reused 'junk' pieces. The primary tip was a work of engineering, made up of eight plastic pipes set on a plastic gauge, with holes filled with epoxy putty and precisely carved. The trident, which was created to exude strength, underwent a similar process of improvement utilizing plastic boards, pipes, and junk pieces, with the pattern inspired by the "Nidhoggr" Heavy Scythe. 

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