OK I found this info on Wikipedia. I thought the stuff was an injection molded material.
"CyberSkin is the brand-name of a soft elastomer material that is intended to emulate the feel of human skin. It is made by the adult toy manufacturer Topco Sales. The company states that the technology behind CyberSkin is a "new Aerospace 601 computerized injection molding machine, originally designed by NASA engineers..."
Similar materials are available under other brand names, such as Ultraskin, Eroskin, Softskin, SoftTouch, Cyber Jel-lee, New supersoft, Futurotic and UR3 (Ultra realistic 3.0). All are soft and stretchy, with a velvety texture that is caused by talcs and cornstarches used to prevent the material becoming unpleasantly sticky.
The materials, from the group of thermal plastic elastomers, are mixtures of polyvinyl chloride and silicone. As such, they are attacked by oil, petroleum, and silicone oils, therefore only water-based lubricants can be used without causing damage."
That gets tough to do with out the heating and molding equipment.
Maybe? you could create some kind of metal piston. A cookie press or a grease gun with no platic parts. Get something made of the stuff you choose to use and heat it in the oven until it melts. A glass test tube might work. Once you know what temperature it melts at, then it's just a process of making the mold you want. You can put layers of wax on your chest (probably want to shave it or maybe butter or grease would work). Once the mold is thick enough, you pop it off and fill it with plaster. Now you have a sculpture of your chest and half the mold. If you kept putting wax on the first part you could get it thick enough to sculpture the other side of the mold. (or get a model to wax thier chest to get the shape you want). Now you have a piece that is exactly what you want made. Plaster it all around so you have a mold. Drill a hole in the top and one on the bottom till you hit the wax inside the mold. These holes have to be the highest and lowest points.
Warm the mold up till the wax runs out of the bottm mold hole. This is called the lost wax pocess.
Fill this mold from the bottom with the desired plastic till it runs out the top. Let it cool. Break the mold off and your done.