I made a remote control plane and painted a little dude inside and flew it into a drone :D Could call it a Kami-Kamazon mission :D
Or if i built a custom dual shotgun cartridge mechanism that could fire from the wings of a RC spitfire :D
OR i bought a nice rocket and turned it into a missile with some available kit.
Personally i think you would get into MORE trouble for making any such thing, go to jail for a very long time, than if you actually used it to shoot down the drone. They dont like people having things like that.
And finally: No one is dumb enough to fire a gun in a built up area anyway, the chance of hitting someone is FAR too high for even the most STUPID person to consider it. So not only will no drones actually fly, there are ways to take them down, but no one is stupid enough to try.