The suggestion to use it as an input device is interesting. There's already an established category of input devices for cursor/pointer control on projected and/or medium-distance screens, in the form of various "air mouse" products. Adesso has a double-duty surface/air mouse model for use with a typical desktop GUI, the WiiMote was effectively an air mouse, and several smart TV models include gesture-tracking features in their remote controls, which can be used to navigate both device menus and online content.
The most effective devices use both a gyroscope and an accelerometer in tandem, for full tracking of spatial orientation and motion in three dimensions. So the biggest (pardon the pun) question is whether the necessary sensor packages could be miniaturized enough to fit into a ring body (along with all of the other required parts, like a battery and transmitting/receiving radios.
But perhaps the closest cousin to a possible Apple Sling Ring remote-input device is the "Tap Strap 2" by TAP, which is almost a "gestural input ring", except that it consists of five interconnected finger-bands — "input brass knuckles", if you like. The sensors on those five bands provide not only 3D gestural pointer input and desktop-surface mousing, but also typing input on a virtual keyboard. A single ring would dispense with all of the surface-based input features. But still, despite having a large, boxy "jewel" on the thumb band (housing the battery, radio, gyroscope, haptics, and power button), the Tap Strap 2 pushed its accelerometers out to the pointer and pinky finger bands.
Facebook
Twitter
Instagram