Underbarrel Masterkey | 3D Printed Parts

The Underbarrel Masterkey by Shellington Labs is a compact, spring-powered shotgun platform designed to mount beneath your primary blaster via standard Picatinny rail systems. This listing covers the 3D printed components only, making it ideal for builders who already have the hardware or want to customize their build from the ground up. Its space-efficient underbarrel form factor adds close-range versatility while maintaining a clean, balanced primary setup.

Inspired by classic underbarrel launchers such as the M203 and GP-25, the Masterkey combines iconic styling with modern foam-blaster design. Built around Silly Shell compatibility, it supports a wide variety of ammunition types and delivers strong performance in a compact package. These printed parts provide the foundation for a functional, tactical underbarrel shotgun that integrates seamlessly into modular and competitive loadouts.

Product Note: This listing is for 3D printed parts only, supplied in the customer’s selected color. Hardware, springs, shells, and mounting accessories are sold separately.

Features:

• 3D printed component set for the Shellington Labs Underbarrel Masterkey
• Spring-powered, Silly Shell–fed shotgun platform design
• Designed for under-barrel mounting via standard Picatinny rail systems
• Inspired by classic underbarrel launchers such as the M203 and GP-25
• Space-efficient design delivering approximately 80% of Spring Thunder performance when fully built
• Ideal for custom builds, modular loadouts, and close-range secondary fire solutions

Product Resources:

• 3D Files
• Video Assembly Instructions
• Silly Shells

Included:

• Underbarrel Masterkey 3D Printed Parts ONLY

Licensed Retailer: Ideal Foam Blaster (IFB) is an authorized retailer for PiggyFoam Products.