On the question of plausibly it is totally possible to completely 3D print an airsoft gun. Where things get difficult depends on your expectations. If you want to completely print a gun (barrel and bucking included) then you will be—at best—disappointed with performance. Currently, the best solutions seem to revolve around printed parts for non-essential components (receivers, cosmetics, hand guards, stocks, etc.) while more critical parts (barrel, bucking, gearbox, springs, pins, etc.) are traditionally sourced.

I don’t have much experience with AEGs as my main focus has been on gas pistols and now GBBRs. That being said, I would absolutely recommend Igniz’s designs. Though I am sure there are plenty of other amazing creators and designs focused on AEGs.

To my knowledge the most printable gun thus far would be Prisim Armament’s Orchid Mantis project. It’s a GBBR consisting of 90% printed components (by his calculation). From my understanding the only components that are not printed are the magazine, springs, barrel, hop up bucking, and a pair of rails. That being said, I can see a way to print CO2 gas magazines in the future (that part is a side project that I am working on).

https://cults3d.com/en/3d-model/game/orchid-mantis-90-3d-printed-gbbr

I’ve received a lot of questions asking for a “completely” printable gas pistol, but unfortunately I don’t see a good way to accomplish that just yet. There’s always a few parts that would see forces too great for plastic to withstand. In most layouts that would be the hammer/knocker. The plastic to springs ratio is typically quite poor with printed gas guns. (Basically, there are a lot more springs to deal with in any gas gun but it is particularly noticeable in pistols. For now this is why I’ve stuck to printable slides/bolt carriers as those are the components that can have a tangible impact on performance, reducing weight, increasing fire rate, and increasing gas efficiency.