[elorqxjx] Cube interface

We imagine an interface for a virtual Rubik's cube of arbitrarily many layers.

Rotate a rigid cube containing accelerometers.  The orientation of the virtual cube changes on screen.

How large should this physical cube be for best manipulation?  Radically, not a cube but a small sphere held between two fingers.  Slightly flattened to keep your accelerometer-packed expensive marble from rolling away.  Manipulation resembles contact juggling.

Rotate the cube so that the desired face to turn faces a virtual arm of fixed orientation.

A keyboard with 4 buttons.  Two buttons move a virtual arm in and out, controlling the number of layers which will be turned.  Two more buttons control the direction of the twist.  A joystick or slider could also work.

Alternatively, for a small number of layers, a matrix of 2xN buttons for directly choosing the layer and direction.