I hope this thread will answer any questions any of you might have. Fiberglassing is definitely not hard but it is very time consuming. This site has some pretty decent info about how to make custom kicks
http://web.njit.edu/%7Ecas1383/proj/main/ I might add that I embellished on this, but his step-by-step process might explain anything I leave out.
You will need to make a template of the kickpanel out of cardboard or fiberboard or equivalent. You can use this one template for both sides of the cab.
(1) Put down a couple sheets of foil, and lay out some fiberglass cloth or mat. You want it to be perfectly flat, as this will be the backing of the kickpanel and the flatness will determine the fit. Soak the fiberglass resin into the mat and let it dry well. When it is dry, use your kickpanel template to cut out the part you will be keeping.
I also ripped a couple of 1/2" wood dowels in half, and glued them all around the edge of the the fiberglass. This way, the edge will be rounded when I wrapped the panel in fabric later on.
(2) Cut out some rings to mount your sub and tweeter on. Position these rings where you want them to be and at the angle you desire and cut dowels the length they need to be to hold the speaker where you want it. I used a jigsaw on my rings, and the wood I used was 1/2" MDF.
(3) You need to cover the kickpanel in regular fabric first. Unfortunately, I have no pics of this step but I used some extra green fabric I had in the house. I wrapped it around the panel, and stapled this around the edge first so I could reposition it if necessary, and then hot-glued it to hold it permanently in place. Soak some fiberglass resin into the fabric to make it stiff enough to hold the fiberglass up and not sag.
(4) Time to start 'glassing. This is a very critical step, you want to put it down as smoothly as possible so you don't have to spend hours adding and sanding bondo. I laid down little pieces of mat rather than one big piece so I could mold it better. I used three layers total; let each layer dry before adding the next.
(5) Scuff sand the panel, and sand any high spots. Since you have a couple layers of fiberglass, you will be able to knock out small bumps, but be careful not to sand through and make a hole in the panel. Also cut out the holes for your sub and tweeter now. Test fit the panel in the truck. Make sure that you don't need to tweak it at all, grind down an edge or something like that.
(6) Put a coat of primer on the panel. Even if you are going to be covering it later, primer shows up the surface imperfections. Add some filler (Bondo or other) to the low spots, and when dry, sand it and prime again. I did this several times to mine to make it perfectly flat. After the final primer coat, add your glaze if necessary, and put your final coat of paint on it.
(7) Covering them in vinyl will take some time. I used hot glue which works very well. If it is too stiff, you can use a hair dryer to soften it up a bit, or you can simply chunk the whole piece of vinyl in the dryer for a while. This makes it much easier to work with. Notice that I cut out the back of my panel. I did this for easy access to the speakers, wiring, etc. You can take out the dowels now too since they are unnecessary.
(8) Put them in the truck! I used a piece of Velcro running along the edge to hold it in place, but a couple of screws or trim clips would work as well..whatever works for you.
And you are done, that's all there is to do. I hope this write-up helped anyone contemplating making their own panels.
Good luck!