Custom Fiberglass Moldings - Break The Mold

Pappas began by creating scale models of the design he has in mind. He did not have a precise equation for the scale, so he ended up reworking some of the molded pieces on the car—sort of like doing sculpture in fiber-glass. (That approach may be too time-consuming for many kit builders, so instead we recommend measuring twice and cutting once, and using simple equations such as 1 inch equals 1 foot.)

Using a combination of wood, dry-wall compound, and Bondo, Pappas sculpted the models’ shapes to his liking, though he expects to make further changes when he works in the full-size body. At the rear is the grid he developed to extrapolate measurements on the body at regular intervals—called stations, in technical terms—which provide reference points for building the molds.

Note the mold Pappas created for one side of the car. The same pieces can be used for the other side simply by reversing them, as long as you’re careful during disassembly.

Each station is a piece of 3/4-inch plywood positioned on edge. Pappas scribed the curves with a piece of cardboard and then cut them with a jigsaw.

The PVC skin is 1/4 inch thick with a foam core. It’s available from most plastic suppliers as it is often used to create signs. We suggested heating the material in warm or hot water to make it easier to bend on compound curves. Another skin material we’ve heard of using is polyethylene (a thicker version of the stuff used to make milk jugs), courtesy of Henry “Rodster” Caroselli, of Caroselli Design.

Once the various plywood stations have been cut and shaped for forming the contours, it’s important to brace them securely with a framework of two-by-fours and plywood. Pappas had already produced a rear valance piece, shown here being held up against the side mold to check for fit.

It’s important to allow an extra 1/8 to 1/4 inch for the thickness of the PVC skin that will form the sur-face of the mold, and also additional clearance for the inner surface of the part, since the finished laminate will be at least 1/4 inch thick. The mold surface must be coated with mold-release wax (Meguiar’s is one brand) prior to laying up the fiberglass. Otherwise the part will stick to the PVC skin, and you’ll have a real mess on your hands.

Pappas developed an ingenious combination of various plywood shapes, PVC tubing, and wooden dowels to create compound curves and to reinforce the structure. It’s all held together with drywall screws of various sizes for ease of disassembly.

The PVC skin is attached to the frame with screws as well, and the dimples and seams are filled with Bondo or wax.

At this stage we recommend following the same approach used by car painters—the more prep work you do now, the better the results at the other end. Don’t be in a hurry. Try to create as smooth a surface as possible, so you don’t end up having to grind away excess fiberglass for a year and a day.

To see how the parts turn out, we helped Pappas disassemble the nosepiece he had already laid up. We worked up a good sweat just tearing it all apart.

As long as you don’t plan to reuse the pieces (such as for the sides of the car), you don’t have to be all that careful with the wood.

However, when using a pry bar, don’t brace it against the glass, which is too flexible anyway, because you may end up cracking or puncturing the piece and damaging the gelcoat.

Despite thorough mixing of the resin and catalyst, not all of the lamination cured, even after sitting for a week. Pappas used a heat gun on the sticky areas to help kick off the resin. To prevent this from happening, be sure to use fresh materials (check for dates on the packaging), and check the temperature and humidity before proceeding so you can adjust the amount of catalyst as needed. After applying the gelcoat (a paint-brush application is sufficient, since further finishing will be done after curing), successive layers of fiberglass should be added while the surface is still tacky so they stick together better. Don’t wait too long, or the inter-laminar bonds will become weaker.

Fit the pieces to the car frame.

Since the pieces were not scaled exactly to the car, Pappas cut the nosepiece into sections, which allowed him to make changes as he went along by trimming and reglassing them together. He also trimmed some of the car’s metal frame.

Making a mold frame for the hood required running a center stringer first as a reference point.

Again, note how the curves of the plywood stations define the shape the skin.

Measuring clearance is particularly important here, since there has to be enough room to shut the hood without damage and also cause no interference with the mechanicals or radiator cap.

We’ll catch up with Pappas at a later installment to see how his project is coming along.

Although most kit builders don’t normally need to concern themselves with creating fiberglass molds, this skill can come in handy when a body part is damaged and the original compo-nent is no longer available. In other instances, you may want to add a custom touch to your bodywork, make a unique component, or in the case of an ambitious builder such as Dan Pappas, create an entire body from scratch. He’s planning on creating a Ferrari-inspired shape on a short-wheelbase Datsun 280ZX.

Pappas developed a comparatively cheap and ingenious method for creating fiberglass molds in his garage using simple power tools and ordinary materials. You might not want to take on the scope of his buildup (we’ve kidded him about having a bit too much time on his hands), but the methods he employs could be applied to all sorts of smaller-scale projects. We’ll be checking in with him periodically to follow along with his trials and tribulations, and we’ll throw in a few suggestions and words of encouragement.

Incidentally, we came across Pappas’ project quite by accident, when your author happened to be walking on the beach. I saw Pappas reading some really old back issues of Kit Car while he was working on his tan, and figured this guy must be a hard-core kit enthusiast (the issues he had dated back nearly a decade). I introduced myself as the former editor of the magazines he was reading and then learned of his project that he is now letting us in on. He may end up regretting us breathing over his shoulder, but we’ll try to make it worth his while. If other readers have similar build projects to share, we’d like to hear from you!