Relativity Space (YC W16) Gets a Launch Site at Cape Canaveral
theverge.com
theverge.com
Rocket Lab is also using 3D printing successfully on their process: https://www.rocketlabusa.com/
They sound as ambitious as Tesla was - for using automation in manufacturing Model 3.
Another startup idea - lets 3D print electric cars
https://all3dp.com/4/xev-start-production-3d-printed-electri...
Why not aim to build a fuel factory first, to refuel spacecraft for return trips?
I do agree though that fuel is the most important thing to start making on Mars though. That and air and water.