Who owns a smoking gun for cooking  and is it worth it.  I was thinking about getting one for the time I do not want to use my MAK 2 Star

Never heard of one.
What is it

I've seen Steve Reichlen (sp?) use it on one of his show years ago and have seen stories about bars using one for cocktails.  It seems like a pretty cloudy smoke from what I recall seeing so my assumption would be that whatever you are trying to smoke will taste like an ash tray.

Similar to Lew, I’ve only seen them used for drinks and deserts like covering a bowl of whipped cream with cling wrap then filling it with smoke.

I have one and it works fairly well depending what your trying to use it for. Quick smoked cheese cubes and the like for surprise guests, smoked nuts that kind of thing. Are you smoking meats or something with it? Definitely not. Is it better then using liquid smoke, absolutely in my opinion. Filling a bowl with smoke with cling wrap covering it is how I use the smoking gun. It is manufactured by Breville for those who haven't heard of it.