Host of The Once Bitten Podcast.

Author of Choose Life.

Robin Smith is a Scottish design engineer, inventor and founder with 25 years of experience turning ideas into working products. He co-founded Heat21, which develops compute-backed electric heating systems that recover useful heat from Bitcoin mining.

BTC Map and Other Stuff.

Design Engineer in the Home Mining Space

Duncan – aka “I Am GPIO”

Duncan Coombe is a design engineer and the creative force behind The Solo Mining Co' and multiple other Bitcoin-focused ventures. Known online as “I Am GPIO”, Duncan has been active in Bitcoin since 2011, building a reputation at the intersection of hardware design, mining innovation, and community engagement.

With a background in engineering and product design, Duncan specializes in creating bespoke Bitcoin mining hardware that blends performance, aesthetics, and usability for the home. His projects range from near-silent, decor-friendly solo miners to experimental concepts like mining-powered home heating solutions — all united by a focus on making Bitcoin mining more accessible, sustainable, and inspiring.

Through The Solo Mining Co' and collaborations with pioneers such as GekkoScience, OSMU, Altair Tech, ACS, and countless others, Duncan has helped shape the future of creative hardware design and individual sovereignty in mining. While his core drive is building and engineering, he also has a passion for teaching and training, helping others understand, build, and participate in the mining ecosystem.

Whether speaking as Duncan Coombe or under his moniker “I Am GPIO”, he brings together technical depth, entrepreneurial grit, and a commitment to empowering individuals to participate in Bitcoin mining on their own terms.