First, acquire two 2 in x 2 in x 8 ft pieces of wood, 6 3 in screws, 8 5/8 in screws, two L joints, and a 2 ft x 4 ft x 1 in panel. Some other things you may need are a measuring tape, a pencil, a straight edge, a drill, a saw, and sandpaper.
Next, you have to mark up the wood to cut. One of the 2 in x 2 in x 8ft pieces of wood needs to be marked in the middle/at 4 ft, and the other every two feet/at 2 ft, 4 ft, and 6 ft. Use a measuring tape to measure the distances mark the wood using a pencil. For more precise cuts mark at least two sides of the wood at the cutting point using a straight edge. The 2 ft x 4 ft x 1 in panel needs to be marked down the middle vertically/at 2 ft. Additionally, this panel will need to have 2 in x 2 in squares marked on the two top corners.
Next, cut all of the wood on these lines we drew using a saw. I found it helpful to use two surfaces with a gap between them and to lay the wood there with the mark in the gap to cut. If the cuts aren't perfect, sand them down using the sandpaper.
After this, mark the middle of the two 4 ft x 2 in x 2 in pieces of wood. Position the L joints on these lines so that the shorter sides are in the air, and the middle bend is on the line. Use the 5/8 in screws to screw these in using a drill. Position the cut panel with the 2 in x 2 in x 4 ft pieces of wood positioned inside of the 2 in x 2 in holes with the metal L's below the panel. Drill the 5/8 screws into the panel through the L's.
Then, mark the middle of the top of two 2 in x 2 in x 2 ft wood pieces. Mark the panel's empty corners in the middle of a 2 in x 2 in square. Position them under the panel of wood on the two corners which are empty. Drill the 3 in screws through the top of the panel and into the top of the other wood piece using the marks.
Next, create a capital T out of the two remaining 2 in x 2 in x 2 ft wood pieces. Mark the middle of the top of one, and the horizontal middle of the other and line these marks up to form the T shape. Drill a 3 in screw into the mark to secure the T.
Line the T up so that it rests on the back posts of the chair and is centered. Once in position put marks on the side of the posts so that you don't lose the position. Mark the center of the portion that is lined above the posts and then drill 3 in screws into these marks to secure the T on the two top corners. Lastly, mark the middle of the aligned part below the T and the panel. Drill a screw into this mark, securing the bottom of the T.
Finally, take a seat and enjoy your new chair!