Once a bulk glass material has been produced, it has to be made into something useful. If the aim is to produce some sort of fibre optic, draw towers are used to create glass fibres by heating and stretching a bulk material (or preform) to create long strands. The design and composition of this preform results in different abilities of the fibres once drawn out, such as stronger fibres, more efficient data transmission, or a broader available bandwidths for carrying information.Polishing involves reducing the surface roughness of a substrate by physical means. In the micro and nano worlds this is typically done to alter a surfaces optical properties, making it more reflective or transparent depending on the substrate.