The term "acrylic" is used for products that contain a substance delived from acrylic acid or a related compound. Most often, it is used to describe a clear, glass-like plastic known as poly(methyl) methacrylate (PMMA). PMMA, also called acrylic glass, has properties that make it a better choice for many products that might otherwise be made of glass. There are two basic types: extruded and cast.
extruded and cast acrylic.
Extruded acrylic is cheaper, but transparency is not so good as cast.