Time: 2 hours
Staple gun or glue
Box cutter or scissors
Wooden post. Cats like to be able to stretch while they scratch, so make sure the post is longer than your cat. I used a 4x4 that's 27 inches long.
Wooden base. This should be heavy enough to support the post. I found a nice round piece at the hardware store for $4, but plywood may work as well. You'll probably want it to be at least 16 inches square.
Two 3-inch wood screws
Carpet (optional). I used less than 1 square foot of a carpet runner to cover just the vertical post. Avoid carpets with a loop pile, which can unravel quickly when a cat scratches.
Padding (optional). If you have hardwood floors, you're probably going to want to cushion the bottom of the wooden base. I used adhesive felt pads, but another option would be to hot-glue any leftover carpeting to the bottom of the base.