If you're assembling a true parts kit you won't find what you need at the hardware store. You'll need a block to secure the receiver and a barrel nut wrench, a pivot pin installation tool, a buffer tube wrench and a handguard tube wrench for starters. Buy them from Brownell's or borrow them from a friend. This assumes that the barrel and barrel extension are already attached and the bolt headspaces properly. Prepare for a lot of little parts in tight places. If you've never done a build I really encourage a lot of research, an experienced helper, or have it assembled. The tools are not cheap and are job specific, so you won't be able to use your AR10 barrel nut wrench for AR15 for instance. Other little items are handy such as a mag button installation tool, but not necessary, but the half punch pin for the bolt release is almost mandatory if you don't want to mar the receiver driving the pin in. While you're buying tools get real gun screwdrivers and get the right tools for cleaning and maintaining your new rifle. When you're done you can always sell the tools on Ebay if you don't need them any longer.
Assembling the rifle isn't particularly hard as there are plenty of books and videos widely available, but you need to exercise a lot of caution and patience to assemble it right and not damage the finish. Buying matched parts helps a lot, too.