And Best of All, No Questions Asked

I don't imagine one would be too hard to build at all, and for only a few dollars to buy some pipe and stuff. [More]

You wouldn't even have to (or probably want to) fire it as long as it fit the definition of a firearm.  The point here is bang for the buck (with care to make sure you don't get popped on some state infringement).

[Via Florida Guy]