This is a very easy thing to make. It would take anyone with a normal amount of tools, a half hour to make one of them as all you need is a solenoid and a mount for the gun. The stupid part is that they put it on TV, so now every dumb ass in the world who has $100 bucks for the drone, "at Sam's" and a pistol, can make one and probably shoot themselves or their friends in the process.
Doesn't anyone ever think it's a bad idea to show kids and immature adults stuff like this, when you know they are going to copy it.
There have to be thousands of these being made right now.
By the way, if you ever have gone to an event where they fly all sorts of RC planes helicopters etc, any of them could be fitted with a lot more than a handgun. Some are 15 feet long models of B52 bombers , with 4 engines, and jets that are so fast you can barely see them. This is not a new concern, it just should have been kept away from mass media at this time in our Country's problems. The helicopters could be fitted with real missiles, as far as that goes. Or guided into a building packed with "god knows what". I don't understand why this little drone with a pistol attached has drawn so much attention.
When I went to The Academy of Aeronautics, "back in the 60's". we had these air shows every weekend.
Even mockups of carrier landings , with tail hooks on the planes. My Uncle flew these up until his death and was an avid "RC Model Builder" and Pilot".
It's an old hobby that has thousands of participants throughout the USA.
One thing I don't get, is that you always had to be in a certified field and have a special license to fly these things, no matter what they were considered, planes jet's or Helicopters, and since a Drone is really a Helicopter, it should already be covered by existing laws preventing them from being flown in public areas. Kind of like shooting guns goes. You need a license and a specific area, unless on private property out in an area that has no ordinances preventing this type of actions.
Just like you can't shoot a handgun in midtown Manhattan even with a license.