Engineers at General Electric recently used a 3-D printer to build a jet engine, employing a technique called additive manufacturing. Despite the machine's compact size, the jet engine roared to an impressive 33,000 rotations per minute.

Additive manufacturing is the process of stacking thin 2-D layers of material to create 3-D objects. Traditional manufacturing sees objects carved from larger chunks of material.

In this case, engineers at GE constructed engine parts using a 3-D printer that employs lasers to fuse thin layers of metal. The differently shaped layers are stacked and fused to form the engine parts -- compressor, turbine, nozzle, burner -- from the ground up.

Additive manufacturing isn't new, but engineers, technicians and machinists at GE employed the technology in a novel way. The team was able to melt metal powder, layer upon layer, to construct complex (and combustible) 3-D structures.

The jet engine was more or less a side project, a victory en route to the next generation of aircraft components. The engine is too small to be of any practical use, but it is an impressive proof of concept.

"We wanted to see if we could build a little engine that runs almost entirely out of additive manufacturing parts," one of the engineers said in a press release. "This was a fun side project."

The larger goal for scientists at GE Aviation's Additive Development Center is to employ additive manufacturing techniques in the building of airplanes.

"There are really a lot of benefits to building things through additive," explained Matt Benvie, spokesman for GE Aviation. "You get speed because there's less need for tooling and you go right from a model or idea to making a part. You can also get geometries that just can't be made any other way."

The Federal Aviation Administration recently approved a 3-D printed GE engine part for flight, and the company is currently testing a next-generation engine that uses 19 3-D printed fuel nozzles.