3-engine Cordership is a diagonal c/12 spaceship that was discovered by Paul Tooke on January 12, 2004. Until the 2-engine Cordership was found, it was the Cordership that uses the fewest number of known possible switch engines. Despite this, the 4-engine Cordership is smaller in terms of minimum population (the 2-engine Cordership beating both).
David Bell discovered in 2005 that the 3-engine Cordership can be used to turn a lightweight spaceship 90 degrees as shown below. It could be  constructed with 15 gliders, and Tooke created a gun for this spaceship only a week after its original construction (see 3-engine Cordership gun). In March 2017 Luka Okanishi discovered a three-glider synthesis for a switch engine, which reduced the recipe to only 11 gliders.
The 3-engine Cordership can easily be destroyed by three
eater 2s and four blocks, as shown below. This cleanup reaction was found by Jason Summers.
Dave Greene discovered a glider synthesis for upgrading a switch engine to a wing, which can be repeated to form the complete Cordership. Adam P. Goucher then built a Herschel conduit to convert a glider into a 3-engine Cordership.
3-engine Cordership about to reflect a lightweight spaceship by 90 degrees (click above to open LifeViewer) RLE: here Plaintext: here
149P96H8V8.1 at Heinrich Koenig's Game of Life Object Catalogs