This is something pretty interesting I just ran across: a free book in pdf format detailing how to build your own blowback operated, semi-automatic pistol using a simplified AK design.
The book contains chapters on building the pistol in .22 rimfire, 7.62x25 (probably the cheapest non-rimfire ammo in the world right now) and 9mm, but it could be adapted to .45 ACP, .40 S&W, or any other pistol caliber.
It's actually easier and cheaper to build a legal pistol of this type than a similar rifle, because a rifle must use a certain number of US-made parts and a barrel at least 16" long, whereas a pistol can use all those too-short barrels and foreign-manufacture parts that are cast off by all the hobbyists who are currently building their own AK type rifles.
The foregoing statement assumes the use of existing AK parts, but the book also has a section on building those parts from scratch.
Books like this are a great resource, because home gunsmithing is a wonderful hobby that is still legal in most parts of the country; but also because knowledge cannot be legislated away, although access to information may be denied, and often is. I'll leave that to your own interpretation.
Here is the information; what you do with it is your own responsibility.
BTW, it starts out sounding like spam ad copy, but scroll down: the entire book really is in there, and it is definitely worth reading.