Over the years there were several ideas of input devices i wished would exist or came together from jokes. Some more useful than others.
More useful examples are the 8 key macropad i am still using and the mini joystick made from an Frsky taranis gimbal:
Less useful are the 3d printed mouse and single key keyboard or single rotary encoder knobs initially used for volume control.
But they always make great conversation pieces on Maker Faires.
If you want to build any device yourself check the project logs and files section. For some of them the complete build files are still available but may require some obscure parts.
After starting the OpenFFBoard project demand of more strange input devices decreased a bit but maybe some things will be added in the future again.