The purpose of this research by practice determines how leather can be used as a sustainable material of choice for the future. Using a design-led methodology, this research develops knowledge for guidelines for the sustainable practice in this traditional industry, in order to make leather a material of choice for sustainable future consumer experiences and manufacturing. This investigation updates and re-evaluates old practices of handling leather and presents modern practices using alternative tanning methods, digital manufacturing and upcycling leather wastes into bonded collagenic fibres which address the end-of-life directive in the automotive industry. Finding knowledge gaps through the literature review, this research proposes leather as an ecoinformed material choice (Ashby 2009) and it introduces new practices to the catalogue of working with leather (Waterer 1946; Amberg 2018).

Leather has a future; it is still a material of choice for high-end design applications including vehicle interiors, upholstery and luxury products. It has unique properties including particularly that of aging gracefully and longevity. It can be soft and luxurious, yet tough enough for selfsupporting structures. There is a huge quantity of animal skins and leather produced every year across the world. A rational use of resources suggests that there are considerable environmental benefits by using this material efficiently. This study proposes new ways to use leather which otherwise goes to waste. This includes new systems that I have devised to use leather waste and offcuts, which currently are discarded into landfill or are being incinerated.

My methods address the future of leather by undertaking detailed observations of practice through fieldwork in the UK, Italy and Japan. Also, by prototyping circular practices using leather through hands-on investigation in a design laboratory and tannery environment.

My findings identified collaborative communities which were drawn out in three areas: an actor network map, a leather processing diagram with closed loops and an atlas of locations of leather making. I produced a framework and an accompanying glossary to inform future practice with leather, including composite fabrication and digital manufacturing. In the practice part of this research, several artefacts have been created, demonstrating a potential process for undertaking 'circular' product design. A body of findings resulting from this research were categorised and presented in guidelines aimed at supporting future practice. Physical leather samples and upcycled composite materials from leather shaving waste tested the validity of the guidelines. Here, the studies demonstrate circular systems for production and reclaiming production by-products, through experiment and prototyping.

An outcome of this research highlights the relevance of leather as a material for the circular economy – this is communicated through a handbook that illustrates terms and processes, which it is hoped will inspire makers and users.

The value of this research for design practice is in its exploration of sustainable manufacturing methods and uses of leather, exemplified by providing samples, as well as the creation of the illustrated handbook. For the academic community, its consideration lies in developing design and reframing the position of leather and its by-products in the circular economy, which unlocks value from the reuse, repair, remanufacture, retrieval and recycling of materials and products.