ISS Commander Barry Wilmore holds a freshly-printed wrench. (NASA)

Now that the International Space Station has a 3-D printer, engineers can design new tools on the ground and then beam them up to space.

In September, Made In Space, Inc shipped a 3-D printer to the astronauts at ISS. In November it printed its first object -- a replacement part for itself.

But this is the first time it has printed a specially-designed tool on-demand, which is exactly the kind of work its designers hoped it would do.

"The socket wrench we just manufactured is the first object we designed on the ground and sent digitally to space, on the fly," Made In Space founder Mike Chen wrote on Medium. "This is the first time we’ve ever “emailed” hardware to space."

Why's that so great? Chen and his colleagues were responding to a request from astronaut Barry Wilmore, who needed a ratcheting socket wrench. Until now, that kind of request would take months to fulfill -- Wilmore would have had to wait for the next mission to ISS to carry the tool up.

Instead, Chen and his team designed the wrench for printing, then sent the design up to ISS by way of NASA.

"Because it’s a lot faster to send digital data (which can travel at the speed of light) to space than it is to send physical objects (which involves waiting months to years for a rocket), it makes more sense to 3D-print things in space, when we can, instead of launching them," Chen wrote. And that means that astronauts can do their work more quickly and for less money.

The tech could also be a lifesaver: During the infamous Apollo 13 mission, astronauts were forced to build new Carbon Dioxide scrubbers on the fly out of whatever materials they had on hand. With the lunar module's clean oxygen running out, engineers on the ground raced to design a makeshift solution and relay building instructions to the astronauts on board. But what if they had been able to augment the supplies on board with custom-designed pieces that could be printed at will?

And this quick and cheap way of getting tools into space will only become more useful when we venture beyond our own planet's orbit.

"When we do set up the first human colonies on the moon, Mars and beyond, we won’t use rockets to bring along everything we need," Chen wrote. "We’ll build what we need there, when we need it."