UK-based Plextek Consulting is developing E Ink based panels to cover drones with an aim to make them invisible. Plextek is using 8 inch by 10 inch E Ink panels that are monochrome and lightweight (probably flexible panels). The panels can change their pattern and design and by adding a camera can help camouflage the drone.
Plextek actually wanted to cover military vehicles, but this was too difficult and they switched to drones. Making military vehicles and aircraft invisible using flexible displays is an old idea - I remember the US military playing around with flexible OLEDs back in 1998 or so.