We had originally printed this Morse Code key to operate in "Cootie" mode. You can read about that here. It turns out using a Cootie key is fun and easy on the wrist, but..... learning to operate a Cootie key does take some practice. That said, the automotive spark plug feeler gauge gave such an effortless feel we decided to make a small modification and create a Single Lever Paddle from the original design.
This mod allows usage with an electronic keyer in three terminal mode. The two terminals on the left can be shorted to quickly switch into Cootie mode.