This is a finger mount for a morse code key with an interposer for code keys that are not magnetic.  The interposer is a custom idea based on other friction fit interposers but with significant updates to fit any key and a whole new model.  This parametric model supports different finger sizes and also different key sizes.  It is designed for print-in-place magnets in the interposer and press in magnets on the key.   Make sure to align the magnets between the interposer and the ring.