I've actually built sections of aircraft fuselage from scratch, it's not much different than bending and riveting an AK flat.
Also, like aircraft, firearms have changed little in the past 50 years or so in terms of materials and design.
They are both technologies that if there is a failure, it can cost lives. Even some of the QC processes for gun parts is the same as for aircraft parts, such as MP testing.
I think it's a fairly apt comparison.
I'm not saying you can't do it, just that I don't think it's a good idea. Unless you know what you are doing.
If I could get a kit for an AK I wanted, such as a reasonably priced 5.45 krink kit, I would get it built by someone who builds AKs for a living, even if the cost and wait was greater.
Of course it's all just my ignorant, one sided opinion, and I'm certainly no expert in the field of building kalashnikovs. [URL=http://www.smileyvault.co