I remember reading about this process that will virtually prevent any damage.
Mask off and fill the gaps around the body panels, lights and windows.
Clean the car and apply a mold release (not necessary).
Brush on a brushable silicone mold making material. (silicone does not need mold release in most cases).
Apply enough coats to make it about 3.8" thick. Apply this to the whole car without parting lines.
Plan out parting lines for a fiberglass mold and start making a regular fiberglass mold over top of the silicone.
When the FG mold is done, bolt it back together and lay in the silicone sheet impression of the car.
Now you can layup a complete body inside the silicone mold and again, mold release is not required.
This will prevent any damage to the car. Even if the silicone were to run under a body panel it will stretch and release without a problem.
It is costly but so is damaging a real car.
Jim
Jim, sorry, but I work with silicones a lot, and you are correct...
casting in silicone requires no release agent, but
molding with silicone usually does. Silicone sticks to virtually everything, but virtually nothing sticks to it when cured. The exception is life casting silicones like Body Double and DermaSil. Those are ok to use on human skin and would require no release when molding, but it's still a good idea to use it anyway.
The biggest issue with silicone is the price. Very expensive, but you are correct... that would be a great method. One issue would be the silicone warping with the fiberglass body casting, because it isn't fully secure to the fiberglass mold shell. A way to get around that is by silicone-ing (glueing with silicone) the silicone to the fiberglass and cutting the silicone where the fiberglass dividing lines are. That would secure the silicone so it doesn't pull away and still make the mold seperatable.
Great ideas people.
