Complete garment knitting technology makes it possible to produce a ready-made flat-knitted garment directly on the knitting machine without time-consuming post-knitting processes such as cutting and sewing. Factory Boutique Shima in Japan, a shop for on-demand production of customised knitted garments, uses a complete garment technology for customisation. Here, a customer can be a codesigner and customise a garment in accordance with his/her personal taste in style, material, pattern and colour. The aim of this paper is to present an example of how complete garment knitting technology has been used for mass customisation of knitted products by studying Factory Boutique Shimas's design and production concept. The method employed is an inductive approach based on company visits and interviews.