Cut the two-by-four lumber to 22 1/2 inches long with the saw to create the two front posts, or legs.
Cut the two back posts, or legs, from the four-by-four to measure 40 inches long.
Position the front legs so the side of the leg that will face forward is up. Measure 18 inches up from the bottom of the legs and mark with a pencil. Repeat this process with the back legs.
Lay the back legs on their side. Use a straight edge to draw a diagonal line from the 18 inch mark to the middle of the top end. Use the saw to cut along the line and create an angle to the back legs for the back rest. Make sure the cut is the same on both back legs.
Cut the four horizontal seat support pieces with a saw from the two-by-four. Each piece should measure 20 inches long.
Position the front of the horizontal piece flush against the front of one of the front legs at the 18 inch mark. Position two L brackets at the back of the two pieces and use four 1-inch wood screws to secure the horizontal piece to the leg. Insert a screw at each end of the bracket. Repeat the process with the other front leg at the other end of the front horizontal piece.
Position the back horizontal piece flush against the outside edge of one of the back legs at the 18-inch mark. Secure it in place with two L brackets and 1-inch wood screws. Repeat the process with the other back leg on the other side of the horizontal piece.
Attach the front and back sets of legs together with the side horizontal pieces. Position the side pieces at the 18-inch marks flush with the outside edges of the legs. Attach the horizontal pieces to the legs with two L brackets on each end and 1-inch wood screws.
Cut two 20-inch-long pieces from the two-by-four wood for the top and bottom braces of the back of the rocking chair. Measure 2 inches up from the rear horizontal brace and mark it. Position the bottom back brace flush with the front edge of the back leg. Secure the brace into place with an L bracket and 1-inch wood screws on both ends. Position the top brace 2 inches down from the top of back legs and secure in the same manner as the bottom back brace.
Cut two 16-inch pieces from the two-by-four wood for the vertical back braces. Position the braces evenly between the top and bottom horizontal back braces so the edges are flush with each other. Drive in 1-inch wood screws diagonally through the back of vertical brace and into the horizontal braces to secure the vertical supports into place
Cut a 20-inch-by-20-inch piece of 3/4-inch oak plywood for the seat of the rocker. Position the seat over the supports and secure it into place with 1-inch wood screws through the top of the seat and into the side supports. Insert the first wood screw in the corner of the seat, drilling it through the seat and into the side support brace underneath. Insert another screw every 6 inches around the edge of the seat.
Cut two 18-inch pieces of two-by-four lumber for the armrests. Position the armrest so there is a 1/2-inch overhang at the front of the rocker over the edge of the front leg. The back of the armrest is flush against the front side of the back leg.
Attach the armrests with a 1-inch wood screw through the top of the armrests and into the top of the front legs. Use an L bracket on the underside of the armrests to attach it to the back legs.
Turn the rocking chair upside down and position the premade rocker blades to the bottom of the legs with 2-inch wood screws on both sides of the chair. Turn the chair over and test the rocking motion.