3D printing is a method of manufacturing in which materials, such as plastic or 
metal, are deposited onto one another in layers to produce a three dimensional 
object, such as a pair of eye glasses or other 3D objects. This process 
contrasts with traditional ink-based printers which produce a two dimensional 
object (ink on paper). To date, 3D printing has primarily been used in 
engineering to create engineering prototypes. However, recent advances in 
printing materials have now enabled 3D printers to make objects that are 
comparable with traditionally manufactured items. In contrast with conventional 
printers, 3D printing has the potential to enable mass customisation of goods on 
a large scale and has relevance in medicine including ophthalmology. 3D printing 
has already been proved viable in several medical applications including the 
manufacture of eyeglasses, custom prosthetic devices and dental implants. In 
this review, we discuss the potential for 3D printing to revolutionise 
manufacturing in the same way as the printing press revolutionised conventional 
printing. The applications and limitations of 3D printing are discussed; the 
production process is demonstrated by producing a set of eyeglass frames from 3D 
blueprints.