Step 3: Cutting the Lumber into Pieces
First of all, out of each piece of 5/4 x 6 x 12 board you should cut one piece that's 93 1/2 inches long and another piece that's 45 1/2 inches long. Out of each 12 foot length of board you should have approximately 5 inches left over after you make your two cuts. Do this until you have 8 pieces of 93 1/2 and 8 pieces of 45 1/2 with one full 12 foot board left over.
The left over 5/4 x 6 x 12 board should be cut into a whole bunch of pieces 8 1/4 inches long. The exact size is not critical, it's just that 8 1/4 inches is one and a half times the width of a 5/4 by 6 board (more on this later). If your mitre saw has a cut length scale on the fence you may use that for speed (see photo 4), as the exaxt length is not critical.
Take a 2 x 4 x 8, square off the end and cut a 46 inch piece. Take the left over 50 inch piece and cut it exactly in half (make a mark at 25 inches and cut with the saw blade centered on the mark). Take the two 25 inch pieces and mitre the two ends on a 45 degree angle so that it can be used as a cross brace (see photo 5). Remember to use the rafter square to set the saw to a 45 degree angle (see photo 6), don't use the angle scale. Repeat the whole process for another 2 x 4 x 8. You'll have 2 pieces of 46 inches and 4 mitred cross braces of 25 inches.
If you're going to put on the decorative side caps, you'll need 2 pieces of 2 x 4 x 8 and rip both of them down on the table saw. Each 2 x 4 needs to be quartered (i.e. ripped in half along the 3 1/2 inch side and then ripped in half again on the 1 1/2 side). This should give you 4 pieces that are 1 11/16 inches by 11/16 inches if you have a 1/8 wide blade like I do. Set up the table saw by using the rafter square to square up the fence and a tape measure to position the fence (see photo 7). Do not rely on the distance scale on the table saw! You should also use a roller stand to make your ripping much easier (see photo 8).
Next, take your 4 x 4 x 10, square off the end and cut 8 pieces of 14 3/4 inches out of it. After you're done there should be about 1 1/2 inches of wastage left over.