The "inside mould" approach starts with a set of plans, which include a drawing of the outer shape of the instrument. From these plans a template is constructed, which can be made from thin metal or other materials, and is a flat "half-violin" shape. The template is used to construct a mould, which is a violin-shaped piece of wood, plywood, MDF or similar material approximately 12 mm or 1/2" thick. Edward Herron-Allen, in 1885, specified a "full mould" with dimensions equal to the finished ribs (interior) of the violin.