1. Combo air and mechanical assist (Top left) - This concept would contain an air reservoir which could be either battery or mechanically powered and a mechanical arm to push the post-it from the magazine. I imagine it working in this sequence: Pull back arm (simultaneously the air reservoir is filled and a single note it grabbed), lock is engaged when arm is fully extended (a spring adds tension), pull trigger to disengage lock , air is released as the arm forces the note forward, air propels it off of the arm and out of the gun... repeat. I did some basic testing and found that it would require a significant amount of air without this arm separating it from the post-it stack so this justifies the arm.
2. Formation (Middle right) - I like this concept because the post-its would travel further and they would look like a dart. Unfortunately, even in optimal conditions, the note does not stick together as well as I thought so this won't wont :(.
3. Power Fan (bottom left) - Basically a high powered fan propels a bunch of notes outward, initials thoughts: A) You cannot control the amount of notes shot. B) It would get jammed.... Alot.
So I will proceed with concept 1.