Growing up, Tim Brown discovered he was very good at two things: design and soccer. While playing professional soccer in New Zealand, he was turned off by the flashy logos on most athletic gear. He started making simple canvas shoes for his teammates, but soon discovered a better material: soft merino wool from his country's plentiful sheep. Meanwhile, on the other side of the world, his future business partner Joey Zwillinger was frustrated that most companies lacked a genuine commitment to sustainability. In 2015, Tim and Joey teamed up to create Allbirds, a company with two ambitious goals: create the world's most comfortable shoes, and do it in a way that was completely carbon-neutral. Today, just three years after launch, Allbirds is worth $1.4 billion. PLUS, for our postscript "How You Built That," how Kirby Erdely saw a problem with flying beach umbrellas and developed a new kind of tent stake?with a twist.