Vault Boy DIY Costume Guide

What You’ll Need

Vault Boy’s design relies entirely on bold, clean graphics. Because the character exists as a mid-century cartoon mascot inside a post-apocalyptic universe, the outfit showcases sharp contrasting colors rather than weathered realism or layered tactical gear.

The core silhouette centers on a saturated blue jumpsuit with bright yellow accents running down the collar and torso, paired with heavy utility footwear and an exaggerated cartoon face. Putting this outfit together comes down to getting the yellow striping straight across a solid blue base.

The Vault Jumpsuit Base

A pair of electric blue twill coveralls provides the foundation for the entire build. Industrial work coveralls match the utilitarian aesthetic of Vault-Tec uniforms while providing heavy cotton-poly fabric that holds its structure. Sizing up slightly gives you enough room through the torso and shoulders to move freely, which matters since heavy twill has zero stretch.

Washing the coveralls beforehand removes factory sizing and softens the twill, which helps tape adhere more cleanly to the fabric weave.

Most work coveralls feature a fold-down collar and a long front zipper. Leaving the collar pressed flat gives you a clean surface to attach yellow trim right up to the neckline. If the coveralls include chest pockets, decide early whether to run your striping directly over the pocket flaps or align the tape just inside the zipper seam.

Applying the Yellow Striping

The yellow detailing defines the vault uniform. Yellow duct tape offers a straightforward, durable way to lay down solid contrast bands along the collar edges, down the front zipper flap, and around the wrist cuffs without sewing.

To keep the lines crisp, spread the coveralls flat across a firm table or hard floor before peeling any tape. Run strips along the zipper placket first, smoothing the material down slowly from collar to waist to prevent air pockets or accidental creases in the adhesive. When crossing the waistband, press the tape firmly into the gathered fabric while stretching the elastic slightly so the stripe stays anchored once the suit is worn.

Taping around the wrists and collar requires shorter segments. Cutting tape into clean segments rather than wrapping one continuous piece prevents bunching along curved seams. For the back of the suit, you can slice individual vault numbers from overlapping tape strips on a cutting mat using a ruler and utility blade, then transfer them directly onto the fabric between the shoulder blades.

The Mask and Visibility

The oversized Vault Boy mask instantly establishes the mascot proportions. Because molded full-head masks trap body heat quickly and restrict peripheral vision, check the alignment of the interior eye cutouts before walking through crowded convention floors.

Wearing a snug bandana or balaclava beneath the mask keeps hair away from your eyes and stops loose strands from catching on the plastic interior. If the factory breathing holes feel restricted, carefully enlarging the nostril openings or lower mouth seam with a craft knife creates better air circulation during extended wear.

Footwear

Standard black work boots complete the base of the uniform. Heavy utility boots match the retro-industrial workwear aesthetic of the vault setting without requiring special alterations. You can tuck the pant legs into the boot shafts for a tapered worker look or let the straight-leg hem drape naturally over the laces.

Wiping off excessive scuffs keeps the boots aligned with Vault Boy’s crisp promotional look, though ordinary street wear won’t detract from the cartoon silhouette.