Consider it a jet engine for the Oompa-Loompas. GE engineers working on the future of aircraft manufacturing recently showed off some of their capabilities. They made a simple 3D-printed mini jet engine that roared at 33,000 rotations per minute.

The backpack-sized jet engine was built by a team of technicians, machinists and engineers who work at a GE Aviation’s Additive Development Center outside Cincinnati, a lab focused on developing additive manufacturing, a next-generation technique that can make complex 3D structures by melting metal powder layer upon layer. They built the engine over the course of several years to test the technology’s abilities and to work on a side project together.

The GE team couldn’t build the complexity of a whole commercial aircraft engine into their working model. Instead, they got plans for a simpler engine developed for remote control model planes and customized them for their 3D printing machines. Their final product measures around a foot long by about eight inches tall. When they were finished, they mounted it inside a test cell typically used to try out full-scale engines and fired it up.