This morning I'm thinking about quadcopters. These, like all rotorcraft, fly by force of will. Unlike the graceful wings birds and sailplanes, they beat the air into submission.
It's energy inefficient too. The many spinning props on a quadcopter burn through batteries really fast. Several people have created solutions to this. I propose another.
We have techniques from sewing sails and parade balloons for creating envelopes that inflate into specific 3-d structures. If you disassemble a digital blood pressure machine it has a small air compressor in it. A person that had time and motivation to do so could make a set of inflatable wings that a quad could use for the transit portion of its mission, then deflate and retract them for hovering. It could use the rotors for elevator and aileron control or have traditional control surfaces.
The wings are subject to loading forces and I doubt they would support them with just air pressure. I see this built with a telescoping set of rods inside the wings that are spring loaded to retract. The air pressure extends and inflates the wings. Venting the air causes them to deflate and retract.
That sounds pretty cool.