Floating screen

From Live Cinema Research

Maybe when the arm interface is activated, a stream of nanobots, held in a small container within her wrist, is sprayed into the air. These join together to form the (very thin and therefore almost transparent) screen in front of her face.

They can follow Ping around to some degree, and the colours on the screen are formed by the nanobots themselves changing colour, responding to signals from the implant. When the interface is disabled, either the screen falls apart and drifts off, or somehow finds its way back into the container on her wrist.

Alternatively, the interface automatically detects any other appropriate screen nearby and can use this for display instead. This includes Ping's artworks, the walls in her room, and screens in Big Fish's laboratory.