GE has 3D-printed a working jet engine

The catch: The engine is about the size of an American football, so it’s unlikely to be installed on any commercial planes in the near future. But that doesn’t mean it can’t fly: GE says the engine made from additive processes can spin at up to 33,000 rpm, and is based on a design from a radio-controlled jet engine model plane. (Model jet planes are a big deal for some hobbyists.)