Kevin DB shows the assembly and basic functionality of a 3D-printed double-barrel airsoft shotgun that uses APS/Hakkotsu shells. This details how different components, including the barrel, stock, and trigger mechanism, are fitted together. The demonstration also includes loading airsoft shells into the barrels and operating the trigger. 

Kevin DB shows a 3D printed lever action airsoft rifle with the designs available to download. The kit is a gas-powered design that uses standard Tokyo Marui MWS short or 35-round magazines. It features a completely printable exterior, including a functional bolt and a uniquely redesigned lever-action mechanism.

Kevin DB shows the  assembly of a 3D-printed AKM GBBR. The process begins with the main receiver, followed by the insertion and adjustment of internal components like the bolt carrier and spring assembly. From there, he demonstrates magazine insertion and removal, attachment of the gas tube and handguard, and a partial disassembly to highlight internal workings. 

Kevin DB showcases his one-of-a-kind Custom MK47 Mutant Gas Blowback Rifle. Built on a Tokyo Marui M4 MWS GBB platform, this airsoft gun features a PLA 3D printed upper receiver and bolt carrier, paired with a TM MWS trigger box, custom hammer, and sear. The recoil is enhanced with a 232g steel buffer and a 140% buffer spring. The video concludes with a demonstration of the rifle's semi and full auto capabilities.