"Relativity Space, a rocket manufacturing startup, just secured launching space at Cape Canaveral. Relativity Space hopes to commercialize in 2021 with a near-term plan to deliver satellites to space and a long-term goal to 3D print rockets on Mars. Led by executives trained at Blue Origin and SpaceX, Relativity Space believes that a rocket typically built with 100,000 parts can be 3D printed with fewer than 1,000 parts. So far, the company has printed its engine injector and chamber in just 3 pieces, three orders of magnitude fewer pieces than the 3,000 that traditional manufacturing techniques would have required.
3D printing should not only reduce complexity but also compress manufacturing times and slash costs. Relativity Space expects to 3D print and assemble rockets in just 60 days instead of many months or years. Its metal 3D printer consists of three collaborative robotic arms, controlled by Relativity’s path planning software, that manufacture parts autonomously. Relativity envisions that 95% of the manufacturing will take place without human help, a significant advance given estimates that labor costs account for 80-90% of the typical manufacturing costs of a rocket today. NASA programs cost hundreds of millions of dollars in labor hours, so 3D printing and automation could compress launch costs considerably.
 Source: Verge article linked above"
(via la très bonne newsletter de Ark Invest https://research.ark-invest.com/ark-disrupt-issue-157)