Adjust the table saw blade to cut at a 45-degree angle. Raise the height of the blade so that it will cut through the thickness of the eight boards. Adjust the table saw fence so that the blade will cut just the corner edge off from the boards. Lock the fence in place.
Lay each board flat on the table of the saw one at a time. Slide one 1-by-22-1/2-inch side flush against the fence of the table saw with the 2-by-22-1/2-inch side flush against the table. Guide the boards through the saw to cut a 45-degree edge along one 22-1/2-inch side of each board.
Sand the cut edges of the eight boards with a fine-grit sanding block until they are completely smooth. Always sand in the direction of the wood grain.
Apply a bead of wood glue along each cut edge of the eight boards. Pair up the boards into four sets of two. Join the paired boards along the cut edges. Press the boards firmly together at the joints to form 90-degree angle leg assemblies.
Align two metal corner braces inside of each leg assembly. Position one 2 inches in from the top and bottom edges. Drive the included screws through the mounting holes in the braces into the leg boards with a screw gun. Wipe off any glue that oozes out with a damp cloth. Allow the glue to dry for 24 hours before working with the leg assemblies.