Another vote for making Duct Tape a Caliber I pick

[iconoplast]

Single-shot, Disposable Shotgun

Materials Needed:

Shotshell
Paper strip, approx. 2" wide, several feet long (or multiple strips)
Paper strip, approx. 3-4" wide, 2-3' long: Alternate - wooden dowel, diameter equal to shotshell
Elastic band (rubber band or inner tube rubber)
Nail (16P is fine)
3 to 5 magazines (yes, the kind you read)
glue, tape, twine

[Krensky]

That's just a Mechanics/Build check at a stiff penalty.

[Gentry]

In addition to the recoil and muzzle blast to which you may already be accustomed, you can also expect a shower of confetti. Think of it as a celebration of the elimination of a goblin. But also remember to carefully brush any off of yourself.

That line makes the whole article worth it.

In fact, the whole tone of the thing reminds me of this:  http://www.buckstix.com/howitzer.htm

[iconoplast]

...
That line makes the whole article worth it.

My Favorite is:
4. Next, take the magazines and sanitize them. By this, I mean to be sure you haven't left an address label with your name and address on them. It would be a terrible shame to go to all this trouble to construct an untraceable weapon only to leave the police your calling card.