Second Years had a Jesmonite workshop yesterday.

From Wikipedia:

Jesmonite is a composite material used in fine arts, crafts, and construction. Jesmonite consists of a gypsum-based material in an acrylic resin.

Jesmonite is a versatile material and is used in several different ways. It is typically used for creating sculptures and other three-dimensional works, but can also be used with other materials as a ground for painting. It can also be used as a surface material in building and construction. It is considered an attractive alternative to other resin-based materials, such as polyester and fiberglass. It can be used for casting and laminating. It is considered durable, flame resistant, and resistant to impact. It can be used to fabricate both small and large objects. When mixed, it accepts colored pigments and metal powders. Its surface can be finished to resemble plaster, stone, metal, and wood.

more info here
http://www.tersus.co.uk/