Try to move the pipe around a lot in the heat to keep from scorching it. **To heat the pipe I am using a propane heater but you can use a torch, a heat gun, an electric or gas stovetop, camp fire, bbq, etc. Keep putting it on the bow to check if it's tight. Tie knots in the string to shorten it one at a time. For the string, just tie a loop in each end and make it so it looks just on the long side of the right length. Drill holes and screw the bow into the notch in the stock. File a notch into the limb tips for the string to catch on (called knocks). Then cut / sand the now flattened limb tips into a roughly parabolic shape and smooth out the edges with sand paper. Heat the center 1.5" wide section of the pipe and bend the bow limbs (each half of the pipe) slightly back and upward. Be sure that when you press it the pipe is rotated so that the part that was wider from being pressed between the 2x4s is the part that becomes flat.
The end of the pipe should be completely closed after this pressing. Heat the 3" long sections on both ends of the pipe (one at a time) and press them as shown in picture 6. Once you have done that squirt some hot glue into both ends of the pipe, this will be a filler. Use clamps to push the 2x4s firmly together. 5/8" thick wood spacers should be placed between the 2x4s alongside the pvc pipe to control the final thickness of the pressed pipe. We are going to heat it until it gets soft** then press it between two 2x4 boards. Now you need the 22" long piece of 1/2" sch 40 pvc pipe with the markings on it as shown on the plans. Position it so it starts at the front edge of the arrow trough, is running lengthwise centered side to side. Cut about 10" of it and glue that 10" piece to the bottom of the arrow trough. Cut or sand a 5/16 or 3/8" dowel in half lengthwise, so it is flat on one side. Glue the arrow trough on to the bottom of the magazine walls. The front-to-back line is the trough the arrows ride in, and the side to side line is a notch that catches the bow string. Carve grooves along those lines with a dremmel sanding wheel. There is one line going crossways on the board 12" back from the front (the end without the 1/4" hole is the front), and a line down the center from the front all the way back to the 12" line. Then mark the lines shown in picture 6 on the arrow trough. Once it is dry, sand it so all the layers line up smoothly without rough or uneven edges. Clamp these together or stack weights on them while the glue dries. Then line up the magazine walls and spacers and glue them together (see pictures for position if it is not obvious to you). Sand the bottom edge of the front magazine spacer ("L" shaped one) so it is rounded concave.
For this step you will also need white glue, clamps (or weights), and idealy a dremmel tool or similar rotary sanding tool (but a round file, knife, or even coarse sand paper can work). Get all the magazine parts (on the plans they are labeled magazine walls, magazine spacers, and arrow trough.