A friend of mine that builds fiberglass chemical spray tanks for helicopters showed me a process for making a mold for my seat/cowl and then producing a part (or several) from the mold. I thought I would post the procedure if others want to try it. If you have worked with fiberglass before,its fairly easy but time consuming. If you have not worked with fiberglass before, I would not recommend that you jump into a project like this. You'll need an air compressor and spray gun as well. Materials needed can be obtained from a composites dealer like "Composites Canada". Just google out composites dealers and you'll find more answers there. I won't go into huge detail about mixing hardener with resin or the different weights of fiberglass materials cause it's too damned complicated for me too...read the can...
One more note here. I'm sure that someone reading this will think "well there's a better or different way to do that". There probably is and feel free to add your comments. The guy that showed this procedure is well seasoned in the field and I was very impressed with what he knows. THANKS BOB!
Shown below is the seat/cowl that I made by using the spray foam wood and fiberglass technique. It's somewhat heavy so I'm going to make a mold from it and then make a lightweight part from the mold.
Prepping the part.
This is the part that I'm going to duplicate. It is important for you to know that I went through all the trouble here because I wanted to incorporate the original 1971 tail light. This part I will call the "plug". It was mounted to a flat board for a reason and you'll see why later. Important things to remember here are...the primer used here is epoxy primer (this primer has hardener that needs to be mixed in and applied with a spray gun), not acrylic which is the more commonly used primer for bodywork. The primer you get in a rattle can is acrylic and is not recommended. After you get a few coats of primer on the plug, dry sand and finally wet sand to remove as many imperfections as you can. The smoother you get the surface at this point...the less rework you will have to do when you pull a part from the mold.
Aside from the resin, hardener and fiberglass that you'll need, these products are essential for mold/part fabricating. Mold release wax and coverall film. The wax goes on first and is applied like any other...wax on, wax off. The coverall film shown at right is a very important step in the process. This stuff is applied with your spray gun. No mixing, just dump it in the gun and apply it generously. When dry it will form a very thin film or barrier that resin will not penetrate. So to recap, epoxy primer...sand...apply wax...apply film. The plug is now ready to cover with material.
Next step is to cover the plug with a product called "tooling gel". This stuff is a thick resin goop. Hardener is added and then applied with a brush. Tooling gel is used in the first layer of the mold because it offers a thick shell/layer that will allow you to re-tool or sand out any imperfections that may have existed on the original part. This layer took a couple of days to fully cure.
After the tooling gel has hardened, your fabric layers are ready to apply. It's a very good idea to have all of your layers preselected and precut. If you have worked with resin/hardener before, you are aware that when resin starts to "kick" things start happening real fast. A good technique for laying in the resin/fabric is to use a cheap disposable paint brush and "dab" all around to remove air bubbles. For this mold, I have chosen the 5 layers as shown. The first 2 layers are called "veil". Veil is very thin and is good for conforming to tight corners and curves. This will minimize any air pockets. I applied both layers at the same time and left it overnight. The 3rd and 4th layers are similar to veil but much thicker and was referred to as "chop". The 5th layer is beefier yet and is a combination of chop and weave.
Here is the mold after the tooling gel and 5 fabric layers. Ready to separate from the plug.
Excess material around the outer edges was ground off and the mold is separated from the plug. The mold is a solid 3/16" to 1/4". I will now be able to mass produce the same part should the need arise.
Now on to the second stage of the process...Making the original part.
Clean the mold with soap and water. The same process that was used to coat the plug with (wax and coverall film) is used to coat the mold with. After that has dried the first layer to go on is the "gel coat" layer. This is the white layer (shown below) and was sprayed in with a gun. (Oops, forgot to mention that a special gun is required here. About $60.00 from the composites store). you could brush it in with good results but will require 2-3 coats.
Once again, predetermine how many layers you want and precut all of them before you start. For my part, I'm using 5 layers of common fiberglass weave or cloth followed by a final 6th layer of chop.
After 6 layers of fabric/chop was applied, The final part is ready to be released from the mold. Note. the black section inside the hump was a piece of carbon fiber that we had laying around. It was not necessary to use it.
Below is the final result just pulled out of the mold. You can see the white color which is the gel coat. The stuff that is being peeled off is the "coverall film" that I mentioned earlier. It is easily washed off with soap and water.
And finally, here is the part after trimming, cutting the "glove box" hole, epoxying a piece in the bottom of the cowl, mounting system etc. I had to fabricate the aluminum piece to mount the tail light and license plate to. I still have to add the decals and a few coats of clear coat to finish completely. Oh yea...and a trip to the seat upolsterer.
I have added this pic as a tail light comparison with a stock 71 CB750 . I wanted the original 1971 Honda tail light to fit well with the seat/cowl.