Step 2: The tools
First, there are a number of tasks involved in building this workbench that can be done faster, easier, and with more precision, on more sophisticated tools. If you have a miter saw, a table saw, a drill press, or a router table, you will definitely want to use them.
Second, if you do build this with a drill, a circular saw, and a hand-held router, you will need a few jigs and fixtures, and some specialized bits. And there are some places where other hand tools would make things easier.
In addition to the drill, circ-saw, and router, I used a belt sander, a random orbital palm sander, and a jig saw. Plus a screwdriver, a wrench, a hacksaw, and other miscellany.
For the drill, I ended up purchasing a Wolfcraft drill guide. If you think you can free-hand drill a hole through 3-1/2" of wood, and have the exit hole appear within 1/16" of where you intended, go for it. I cannot.
For the saw you'll need a crosscut blade and a plywood blade.
For the router you'll need a a 3/8" straight bit, an edge guide, 1/4"- and 1/8"-radius roundover bits, and a flush-trim bit with at least a 1-1/2" cutting length. Bits of this size are available only for a 1/2" collet. Some routers are capable of using multiple collet sizes. I was fool enough to buy a router that only had a 1/4" collet. More on that, later.
For the drill, other than normal twist bits, you'll need a 3/8" brad-point bit, a 1" Forstner bit, a 3/4" Forstner bit, most likely several 3/4" spade bits - or you can resharpen the one if you like, and a 3/8" counter-sink bit.
And you'll need a workbench.
I know, if you had a workbench, you wouldn't be building a workbench. Even so, you'll need some sort of work surface, even if it isn't as stable or capable as a proper bench. The traditional solution is to throw a hollow-core door over a couple of saw horses. The advantage of hollow core doors is that they're flat, stiff, and cheap. I used a folding table and a hollow core door I had bought for a future project.