Rocketry is wild, and [Foaly] is sharing build and design details of the Cortex 2 mini rocket which is entirely 3D printed. Don’t let that fool you into thinking it is in any way a gimmick ...

and decided to create something approximating more grown up rocket designs. The result was a 3D-printed turbopump for fuel delivery. The design is not dissimilar from a turbocharger in a car.