A quick look at this kit by Caffel of this 3D printed kit that is available on Cults3D. This system is designed to feed proprietary 3D-printed shells from a dedicated front-loading magazine. Concurrently, the standard AAP-01 magazine handles the supply of BBs and gas, ensuring the core firing mechanism remains intact.

CaffeL demonstrates a 3D printed shell ejecting kit that converts the Action Army AAP-01 GBB pistol into an AK-style carbine. While its signature feature is shell ejection, the kit is designed to function as a regular carbine conversion even without the shells installed, making shell ejection an optional feature. For external attachments, the outer barrel is equipped with a 14mm CCW thread, allowing the use of various accessories via an adapter.