Making Rubber Molds for Casting Plastic & Sculpey

Make copies of simple objects with a rubber mold.

Craft artisans often use plastic and Sculpey clay in a variety of projects. These materials can be used with a rubber mold to reproduce existing forms, which is useful if you are working on something that needs many repetitions of a shape or pattern. You will make this mold with latex molding rubber and cheesecloth, both of which are available at most hobby shops and craft stores. Once your mold is finished, you can use it to make dozens of copies.

Things You'll Need

• Object to be molded
• Acrylic enamel spray
• Wax paper
• Latex molding rubber
• Cheap paint brush
• Cheesecloth
• Scissors

Instructions

1. Spray two coats of acrylic enamel spray onto the object to be molded, if it is made of a porous material such as foam or plaster. Allow each coat to dry completely.

2. Place the object onto a sheet of wax paper.

3. Brush a thin coat of latex molding rubber onto the surface of the object, then dry it with a hair dryer.

4. Apply another 10 thin coats of molding rubber, drying each one before adding the next.

5. Cut cheesecloth into 4-inch squares.

6. Brush another coat of molding rubber onto the mold, then press squares of cheesecloth into it.

7. Brush more rubber onto the cheesecloth, encapsulating it completely.

8. Add four more layers of cheesecloth and rubber, then let the entire mold dry overnight.

9. Peel the mold off of the object. It can now be filled with liquid plastic resin, or have soft Sculpey pressed into it.

Tips & Warnings

• Do not get molding rubber in your hair or clothing. It will be very difficult to remove.

References

• Model Train: Latex Mold Making
• "The Prop Builder's Molding and Casting Handbook"; Thurston James; 1989