I've built a couple of m16 A1 Viet Nam era parts kits. The upper is really easy to put together. Blue is right about the tools and you'll spend as much shipping as you will for the tools. The original A1 FSB uses taper pins to mount which needs to be done by a smith. Get a drilled barrell and FSB for roll pins and you're golden. Plenty of vids how to build it.
