If you are mechanically inclined, you can assemble an AR lower (from a parts kit and a stripped lower) with no issues whatsoever and almost no special tools ... I'm thinking about what I use and, IIRC, the only tools I need that aren't in a "normal toolbox" are a set of punches, a set of roll pin punches and a small hammer. I find that it helps to have a small block of nylon or wood to support things. Oh ... if you go with the adjustable stock, then you will also need some kind of spanner wrench to tighten the big nut on that part. The nice thing is that even if you just assemble all the parts, you end up with a good knowledge base with respect to how it works.
Saands