Now I am imagining a typewriter with just two huge round buttons, next to each other horizontally, and a spacebar bellow them:
*-----* *-----*
| | | |
| ● | | Ω |
| | | |
*-----* *-----*
[================]
A press of each round button rotates the typing ball accordingly, pressing the space prints the chosen letter and resets the ball to the neutral state. This whole thing should probably be electric lest you'd have to press the space bar by smashing it with both fists.
Now remove the spacebar, combine the two buttons into a single one for "tone" and adapt it to morse code. All the buttons still do only one thing and now there's only one button!
And, you don't have to worry about what to do in the case that someone hits the "rotate ball" button while it's still rotating.