Marcin Jakubowski built a tractor in six days. Then he told the world how to do it: he made the designs, the budget and an instructional video available free online. A farmer and technologist and the founder of Open Source Ecology, Jakubowski has identified the 50 most important machines required for modern life—from the soil pulverizer to the oven—and is working to make a prototype of a low-cost DIY version of each so that anyone anywhere can build them. “If we can lower the barriers to farming, building and manufacturing,” he says, “then we can unleash massive amounts of human potential.”