ESA - 3D-printed storable-propellant rocket engine design tested

The recent hot firing of a full-scale rocket thrust chamber assembly takes us a step closer to proving 3D-printing for an engine design destined for rocket upper stages, in-orbit transportation applications (kick-stages and space-tugs), microlaunchers, and exploration spacecraft such as a lunar lander and ascent stage on the Moon.

4.0 In-Space Propulsion - NASA

Prototype platform proves capable of 3D printing PEEK at up to 400°C in orbital conditions - 3D Printing Industry

Selected results of hot fire tests of hybrids using 98% HTP and HTPB as

Test Stands – Beyond NERVA

German Aerospace Center (DLR) Designs Liquid Rocket Engine Injector with 3D Systems

Fully 3D printed rocket engine unveiled by Skyroot Aerospace - 3Dnatives

Ariane 6: ESA Space Transportation Program - eoPortal

ESA Tests ALM Rocket Engine - 3D Printing

Fully 3D Printed Rocket Engine Tested

ESA - Propulsion activities

Are there any hand-sized rocket engines? - Space Exploration Stack Exchange