A 3D control peripheral is a physical part of a computer system that a person uses to control the computer in three dimensions of space. Examples include SteamVR controllers and 3D pens.
It is a control peripheral that enables the user to input data in three dimensions easily. It is naturally 3D.
Some control peripherals can enable 3D direct interaction.
The most useful 3D control peripherals use linear representational action or direct action.