Scenic Technologies / PRG created the sets for the introduction of the 2008 Jeep Liberty at the NY Auto Show. Part of the design was a carved rock mountain and a large number of rocks that needed to look “real”. The rocks varied in size from 2 feet across to 8 feet across and they wanted at least 16 different sizes and types, 180 rocks in all.

We located a quarry that had the types of rock called for, and chose the “models’ from the variety available.

"Model" Rocks

They were moved with heavy equipment to our shop and brought inside to warm, as this project was undertaken in the middle of the winter here in New York. We had rigid stands fabricated to hold the rocks up off the floor on pins so we could make the full molds without having to turn the rocks. The largest of them weighed about 6 tons!

Rock Stands

We sprayed silicone mold rubber on them, set shim lines, and then sprayed urethane foam and hard coat mother molds.

Spraying Silicone

Brushing Silicone

Shim Lines

Foam and Hardcoat Shells (Mother Molds)

These molds then had mountings attached so they would fit in our rotocaster. The rock surfaces were cast in a tinted urethane and then filled with open cell urethane foam to produce “nearly real” light weight rocks. They were also semi-flexible because some of them need to fall during the show.

Rotocasting and Foam-Filling

Finished Rocks and Show

Here is a video of the 2008 Liberty unveiling at the Auto Show (via YouTube.com):