That's great until a cow eats your drone. Then you'll need a _really_ big magnet. This probably isn't economically feasible yet, but I'm sure we'll see someth

That's great until a cow eats your drone. Then you'll need a _really_ big magnet. This probably isn't economically feasible yet, but I'm sure we'll see something like this in the next decade or two. And for that matter, such a drone could be cutting the grass or doing other similar jobs.