Lets face it, you probably have an AR-15, maybe a couple of them; and if you don’t already have one, you’ve probably thought about getting or building one.
And, if you don’t already know, there are a few specialized tools you need to build an AR-15, or take one completely apart. The main things you may run into are the barrel nut and the castle nut, but you may also need something for compensators or flash suppressors, etc. I’ve used many tools for these various things, ranging from specialized tools, to off the shelf Craftsmen wrenches.
Many off the shelf tools will work for things like the compensator/flash suppressor and the other various pins, and screws, but for things like the castle nut and free float rail installations, you really need special tools, and one that will hold up to some use.