Casting a Prop Engine Block Using FlexFoam® iT! 17


FlexFoam-iT!® 17 is a 17 lb./cubic ft. (270 kg./m3) flexible urethane foam that is ideal for a variety of art and industrial applications. Like the popular FlexFoam-iT® 25, the 17 is “self skinning”, meaning that the cured foam forms continuous high density skin. With the right amount of back pressure applied during casting, the surface finish of the cured foam approaches that of a urethane elastomer. 

The mix ratio is a convenient 1A:2B by volume. Pot life is 60 seconds and handling time is about 30 minutes at room temperature. Cured foam is strong, bendable and tear resistant.

The foam is easily colored with SO-Strong® color tints or Ignite® fluorescent pigments and is compatible with Smooth-On’s Cast Magic System for creating a variety of finish effects. The foam can also be painted with flexible paints.

Applications for FlexFoam-iT!® 17 include making lightweight, durable props and display pieces, special effects and arts/crafts.

Urban Fox Studios was contracted to make flexible foam motorcycle engine display props for a themed restaurant environment. Required; finished props needed to look exactly like a motorcycle engine. The display pieces would be “child” high and therefore needed to be soft for safety and durable to resist wear and tear.

Materials Used in this Tutorial

Step 1: Preparing Mold