This wasn't just a because-we-can experiment. Metal 3D printing is expensive (the printers alone cost hundreds of thousands of dollars). MIT's printer, a Markforged Mark Two, costs "just" $13,499. That's not exactly an impulse purchase, but it could give small teams a chance at building rockets that would otherwise be impossible with a relatively modest budget. And while it's not stated, it's easy to see larger space agencies using this to keep costs down, especially for rockets that are unlikely to be used more than once or for long durations.

There's a lot to accomplish before that happens. The scientists are researching larger, more resilient motors. Eventually, they're aiming for plastic-hulled rockets powerful enough for flight. Don't be surprised if you one day see lighter, cheaper rockets that only use metal sparingly.