Below is the official blurb but the cut down version is that if you have used modroc or other plaster based scenery items this is just like that but without the weight as its a paper based product. Mix it up with strips of old net curtain (ask your local charity shop) it works just like a plaster bandage
This dry, white, non-toxic modeling material produces objects that are very lightweight, strong and durable.
Sculptamold® is AP Non-Toxic.
Sculptamold® is a dry, white, non-toxic compound that combines the best features of clay, plaster, and papier mache, does not shrink, and is durable for dioramas, 3-D sculptures, model railroad scenery and stage scenery.
After shaking closed bag to thoroughly blend contents, add water to Sculptamold® as directed on bag and begin modelling. Sculptamold® sets in 30 minutes, so prepare only as much as can be used in a half hour of modelling time.
Sculptamold® clings to almost all clean surfaces and can be applied to an armature or any core without fear of cracking. Continue to add Sculptamold® by shaping and modelling layers over the armature. Even though it hardens in half an hour, you can continue to work with it as long as you have to, by adding layers of freshly mixed Sculptamold®.
One three-pound bag of Sculptamold® will make 141.75 cubic inches of solid material. Twelve three-pound bags will make one cubic foot of solid material. Click on the PDF above for complete mixing and modelling instructions.