This is a simple, minimal hardware, side swiper Morse code key. Otherwise known as a "cootie" key.
NOTE: You will want to print the arm on a raft to prevent the leaf spring parts from warping off the bed.
This design only needs five screws, two nuts and one thin washer for assembly. Small solid copper wire will slide through the channels for a cleaner looking result. The printed PLA leaf springs work very well for returning to center. Operation is quite smooth.