In a small factory a couple of miles from Los Angeles International Airport, Ellis and Noone have spent the past two years working to build a rocket using only 3D printers. Their startup, Relativity Space Inc., is betting that removing humans from the manufacturing equation will make rockets way cheaper and faster to produce. The going rate for a rocket launch is about $100 million; Relativity says that in four years its price will be $10 million. “This is the right direction,” says Ellis, the chief executive officer, during the first-ever press tour of the company’s headquarters. “The 3D printing and automation of rockets is inevitable.”

That direction is less obvious than he makes it sound. Although a couple of companies have 3D-printed whole rocket engines and other parts to make them more durable (molten metal shaped into a single part is less vulnerable to wear and tear than a bunch of pieces fitted together), 3D printing tends to be slower and more expensive than old-fashioned welding. Faced with that problem, Relativity decided the solution was to build its own printers.