This arrangement leads to a few complicated welding and machining processes, but surprisingly these obstacles can be overcome by simply printing a rocket engine on a 3D printer. The current engine ...

See how Relativity's Terran 1 rocket got from the 3D printer to the launch pad in these highlights. Credit: Relativity Space ...

Hybrid rocket engines offer perks from both worlds, with simple solid fuel and the ability to throttle down by regulating oxidizer flow. Naturally, [Integza] decided he should try and 3D print one.