How to Make an Auto Body Panel Mold

by Cassandra Tribe
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Mitchell Crandell

You can make an auto body panel mold to repair or customize your vehicle. While it is not difficult process, it is one in which you have to practice working with the modeling, casting and fiberglass molding materials. The results, however, will be exactly what you are looking for and often for a lot less than if you paid someone else to do it.

Step 1

Fill in any areas of the auto body panel that need to be repaired with Bondo, or add to the design of the panel by attaching Plasticine and sculpting it to the shape you want. It is important, in either case, that you sand or smooth the Bondo or Plasticine as close as possible, on the edges, to the original surface of the metal.

Step 2

Coat the entire auto body panel with a thin layer of Vaseline. This will help your mold to release.

Step 3

Cut your Plaster of Paris bandages into 12-inch-long strips. Keep in mind that you will want enough of the bandages to cover your panel with a minimum of three layers of bandage.

Step 4

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Dip the bandages into hot water, one at a time. Draw the bandages through two fingers (as if you were smoothing them) to work the plaster through the cloth and lay the wet bandage on the auto body panel and smooth it down. Work quickly and cover the whole panel, smoothing the hot bandages onto each other.

Step 5

Let the bandages dry overnight and then gently pry up, beginning at the edges and working toward the center, until the cast can be pulled off the panel. Turn the cast over and sand any places where your Plasticine additions or Bondo repair are evident in the smooth plaster inside. The inside of the cast is your mold of your auto body panel.

Step 6

Make an "opposite mold" (for instance, if you have a left fender panel but need the right side) by then casting a fine, thin latex panel in your cast. When the latex has set, remove it from the mold, reverse it (turn the mold inside out). Construct a support system for the latex and, using calipers, measure and compare the depth and rise of the cast with the original piece and build up where necessary with Plasticine. When you have matched the panel, make a mold of it by using these same steps.

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