Tormas are offering cakes.  They symbolize the food offering.  Originally made of dough (in Tibet, roasted barley flour is used,) and also sculpted from butter, they have evolved into elaborately decorated objects.  Since making them is time-consuming, people have begun to use clay, wood and more recently, synthetic substances.  These include resin modeling products, and at least one Asian company produces small, injection-moulded plastic tormas.